Update Sidekiq-cron to fix compatibility issues with Sidekiq 4.2.1

The "Enqueue Now" button would not work in the admin panel due to changes in the Web extension interface: https://github.com/ondrejbartas/sidekiq-cron/commit/88ada926132d4658e3fd370c9f44899b6c88ccaf

Closes #24376

See merge request !7815

Add `null: true` to timestamps in migrations that does not define it

This is to ensure that migrations will still be consitent when we will
upgrade to Rails 5 which default to `null: false` for timestamps
columns.

Fixes #23666.

See merge request !7791

Alert user when logged in user email is not the same as the invitation

## What does this MR do?

Add a note to the invitation page when the logged in user email is not the same as the invitation.

## Why was this MR needed?

Help users to not accept invitations logged in with a wrong account.

## Screenshots (if relevant)

![1](/uploads/78ac6d3db67c9ed60cf74a20ad240d0b/1.png)

## Relevant issues

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/24955

See merge request !7803

CE-specific changes for gitlab-org/gitlab-ee#1137

## What does this MR do?

- gitlab-org/gitlab-ee#1137 is a `technical debt` issue to clean up the EE protected branch access levels (for users and groups) implementation.
- Some of this cleanup bleeds over to code shared by CE and EE, which is why this MR is required.
- An EE-specific MR has also been created: gitlab-org/gitlab-ee!927

See merge request !7821

Fix the width of project avatars in order to adjust alignment within their container element

## What does this MR do?
Adjusts the width of project avatars in order to fix their alignment within the container elements.

## Are there points in the code the reviewer needs to double check?
To make sure there are no unintentional styles changes on unrelated elements.

## Why was this MR needed?
To fix the issue seen below.

## Screenshots (if relevant)
Before: ![Screen_Shot_2016-11-26_at_3.55.58_PM](/uploads/c0012ee7bb5f9e83af41190f71f030fa/Screen_Shot_2016-11-26_at_3.55.58_PM.png)

After: ![Screen_Shot_2016-11-26_at_3.56.17_PM](/uploads/c1236216382e6baa094570c17565e8cf/Screen_Shot_2016-11-26_at_3.56.17_PM.png)

Affected pages: ![Screen_Shot_2016-11-26_at_4.12.38_PM](/uploads/8db6d86a5998843e7b7a755fb4000add/Screen_Shot_2016-11-26_at_4.12.38_PM.png)

## What are the relevant issue numbers?
Closes #24999

See merge request !7772

Changes project dashboard tabs to sentence casing

Changes the nav tab titles on the project dashboard page (```https://gitlab.com/dashboard/projects```) from title casing to sentence casing.

Before: ![Screen_Shot_2016-11-26_at_11.17.23_PM](/uploads/a31c951cf83f7670acee778db9337be5/Screen_Shot_2016-11-26_at_11.17.23_PM.png)

After: ![Screen_Shot_2016-11-26_at_11.17.39_PM](/uploads/a0cb5f6b6771e6f5149750ea1e7beb02/Screen_Shot_2016-11-26_at_11.17.39_PM.png)

Closes #25002

See merge request !7774

Add blue back to sub nav active

## What does this MR do?
Adds blue color back active sub nav tab

## Screenshots (if relevant)
![Screen_Shot_2016-11-29_at_10.00.55_AM](/uploads/b968fce60d8e25e7f0769f6fb045291c/Screen_Shot_2016-11-29_at_10.00.55_AM.png)

## Does this MR meet the acceptance criteria?

- [ ] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
https://gitlab.com/gitlab-org/gitlab-ce/issues/24149

See merge request !7829

Adds hoverstates for collapsed Issue/Merge Request sidebar

This MR is part 1/2 of https://gitlab.com/gitlab-org/gitlab-ce/issues/25011

## What does this MR do?

Adds hoverstates for collapsed Issue/Merge Request sidebar

## Are there points in the code the reviewer needs to double check?


## Why was this MR needed?

We needed hover states on the issue/merge request sidebar

## Screenshots (if relevant)

![2016-11-27_23.39.28](/uploads/adb83f5fa291cc8f89f1a7d7e2577546/2016-11-27_23.39.28.gif)![2016-11-27_23.39.13](/uploads/7018e4272da26cb06efb7c6fe4eae413/2016-11-27_23.39.13.gif)

![2016-11-29_16.05.11](/uploads/fcf9a674aa24cf0e7349a7e439b024fe/2016-11-29_16.05.11.gif)

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #25011

See merge request !7777

New project should be below new group on the welcome screen

## What does this MR do?

Places the group `.blank-slate` above the project's.

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?

## Screenshots (if relevant)

![Screen_Shot_2016-11-26_at_13.52.33](/uploads/a6e28dc54ebfc42f0cff5b46558f4ff0/Screen_Shot_2016-11-26_at_13.52.33.png)

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #24135

See merge request !7770

Remove JSX/React eslint plugins.

## What does this MR do?

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [ ] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

See merge request !7470

Expose timestamps in build entity

## What does this MR do?

This MR exposes timestamps for build entity that is being used by serializers in `app/serializers`. 

## Does this MR meet the acceptance criteria?

- Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing

## What are the relevant issue numbers?

See https://gitlab.com/gitlab-org/gitlab-ce/issues/24844#note_19145053

See merge request !7818

Fix pipelines info being hidden in merge request widget

## What does this MR do?

Reintroduces CSS classes that are necessary for `MergeRequestWidget` to show correct divs.

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- ~~[ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~[ ] API support added~~
- Tests
  - ~~[ ] Added for this feature/bug~~
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

Closes #25055

See merge request !7808

Change airbnb eslint config package to `eslint-config-airbnb-base` and update plugins.

Change `airbnb` to `airbnb-base` for .eslintrc `extends` value.

Added changelog entry

Made sure all plugins and envs are set

Corrected new failing specs

Remove unnecessary database indices

See merge request !7789

The "Enqueue Now" button would not work in the admin panel due to
changes in the Web extension interface.

Closes #24376

Fix broken README.md UX guide link.

See merge request !7805

Fix blob controller spec failure

See merge request !7814

Fix typos in Bitbucket integration docs

[ci skip]

See merge request !7823

- Extract all common {push,merge} access level model code into the
  `ProtectedBranchAccess` module

- Use the HTTP verb to define controller specs

Add setting to enable/disable HTML emails

Closes #24880

See merge request !7749

Add issue search slash command

See merge request !7752

Homogenize sort and filter dropdown toggles

## What does this MR do?

Homogenizes the style of *filter* and *sort* dropdown toggles (aka buttons) related to:
- *issues* (index, new & edit views)
- *issue boards* (index);
- *merge requests* (index, new, edit);
- *projects* (index and "explore");
- *projects admin* (index);
- *groups* (show and "explore");
- *groups admin* (index);
- *users admin* (index);
- *todos* (index);
- *branches* (index);
- *commits* (index);
- *cycle analytics*;
- *network*;
- *forks*;
- *tags* (index);
- *global search*

Some other dropdowns are incidently concerned:
- project admin (show);
- assigne/due date/milestone/label dropdowns on the issue and board sidebars;
- stage dropdown on the build sidebar;
- merge request and comparison dropdowns for choosing forks and branches;
- ref switcher (e.g. in the blob (show) view or in the graphs view);

Dropdown toggles concerned by #24150 but not covered in this MR:
- Dropdowns for selection MR versions to be compared (in the "Changes" tab of an MR);
- Dropdowns that bring up a list of actions:
  - "Settings" dropdowns (such as the one found on the upper-right corner of all project pages);
  - The download/action/notifications buttons on the main project page;
  - Dropdowns located inside of list items (on list of pipelines, users and groups, for instance);
  - The "Options" button on the commit (show) view;
  - The "+" button on the tree explorer (for creating files, branches, tags, ...)

### TODO
- [ ] Update ui.html if needed

## Are there points in the code the reviewer needs to double check?

Am I changing any other dropdown toggle than listed above?

## Why was this MR needed?

For #24150

## Screenshots (if relevant)

### Issue Index

**Before:**
![issue-index-before](/uploads/1aa358b0b9e79fd3a7467b57cd2b03ec/issue-index-before.png)

**After:**
![issue-index-after](/uploads/7a4159e8927d456ed3f4390072174e49/issue-index-after.png)

### Issue New

**Before:**
![issue-new-before](/uploads/fcfb9c39d2ff8f00827f52d60db5c114/issue-new-before.png)

**After:**
![issue-new-after](/uploads/a0b151d257d8f3e8f98a2873427362ee/issue-new-after.png)

### Merge Request Branch Selector

**Before:**
![merge-request-new-before](/uploads/8dd7b6e8ea38af7aced743386bfb83ca/merge-request-new-before.png)

**After:**
![merge-request-new-after](/uploads/38ad8f5a315344b3bab7e936a84acf7e/merge-request-new-after.png)

### Global Search
![global-search-after](/uploads/f2912b7d91fd286028cb9481d2d53a82/global-search-after.png)

### Cycle Analytics
![cycle-analytics-after](/uploads/248d5ca360bb510aa0f0bfa8a1a00aae/cycle-analytics-after.png)


## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~API support added~~
- Tests
  - ~~Added for this feature/bug~~
  - [ ] All builds are passing
- ~~Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)~~
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

#24150

See merge request !7583

Hide project variables values by default

Add a button to reveal/hide the values to help prevent accidental disclosure of sensitive information from wandering on a page.

![hide-vars](/uploads/5b5eeef9b4650776b529b780998bbb1b/hide-vars.gif)    

Closes #21358

See merge request !7731

Refactor issuable description and metadata form sections

Continuation of https://gitlab.com/gitlab-org/gitlab-ce/issues/23864.

Brother of gitlab-org/gitlab-ee!916.

See merge request !7758

Add diff hunks to notification emails

Add diff hunks to notification emails. Continued from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5855 - thanks @hoopes!

This also fixes an issue where the + / - prefixes were missing from diffs in emails.

Screenshots (from my browser) of the HTML emails, along with text screenshots 😛

![image](/uploads/cb31400becf5149d40c8bb98a655aa93/image.png)

```
New comment for Merge Request !1 on app/views/admin/builds/index.html.haml:

http://localhost:3000/gitlab-org/gitlab-ce/merge_requests/1#note_1023

>          Finished

This is a comment at the top of a match section.
```

![image](/uploads/704dd3845797530697a27f5c1953c053/image.png)

```
New comment for Merge Request !1 on app/views/admin/builds/index.html.haml:

http://localhost:3000/gitlab-org/gitlab-ce/merge_requests/1#note_1022

>          Finished
>          %span.badge.js-running-count= @all_builds.finished.count(:id)
>  
> -    %li{class: ('active' if @scope == 'all')}
> -      = link_to admin_builds_path(scope: :all) do
> -        All
> -        %span.badge.js-totalbuilds-count= @all_builds.count(:id)
> -
>  .gray-content-block
>    #{(@scope || 'running').capitalize} builds
>  

This is a comment at the bottom of a match section.
```

![image](/uploads/4063f3d9738aea8ebf3c0e690d0eddee/image.png)

```
New comment for Merge Request !1 on app/views/admin/builds/index.html.haml:

http://localhost:3000/gitlab-org/gitlab-ce/merge_requests/1#note_1024

>          = link_to 'Cancel all', cancel_all_admin_builds_path, data: { confirm: 'Are you sure?' }, class: 'btn btn-danger', method: :post
>  
>    %ul.center-top-menu
> -    %li{class: ('active' if @scope.nil?)}
> +    %li{class: ('active' if @scope == 'all')}
>        = link_to admin_builds_path do
> +        All

This is a comment with some deleted and added lines above it.
```

Closes #21027, closes #24340.

See merge request !7660

Replace issue access checks with use of IssuableFinder

Split from !2024 to partially solve https://gitlab.com/gitlab-org/gitlab-ce/issues/23867

## Which fixes are in this MR?

⚠ - Potentially untested  
💣 - No test coverage  
🚥 - Test coverage of some sort exists (a test failed when error raised)  
🚦 - Test coverage of return value (a test failed when nil used)  
✅ - Permissions check tested

### Issue lookup with access check

Using `visible_to_user` likely makes these security issues too. See [Code smells](#code-smells).

- [x] 🚦 app/finders/notes_finder.rb:15 [`visible_to_user`]
- [x] 🚥 app/views/layouts/nav/_project.html.haml:73 [`visible_to_user`] [`.count`]
- [x] ✅ app/services/merge_requests/build_service.rb:84 [`issue.try(:confidential?)`]
- [x] ✅ lib/api/issues.rb:112 [`visible_to_user`]
  - CHANGELOG: Prevented API returning issues set to 'Only team members' to everyone
- [x] ✅ lib/api/helpers.rb:126 [`can?(current_user, :read_issue, issue)`] Maybe here too?
- [x] ✅ lib/gitlab/search_results.rb:53 [`visible_to_user`]

### Previous discussions
- [ ] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#b2ff264eddf9819d7693c14ae213d941494fe2b3_128_126
- [ ] https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#7b6375270d22f880bdcb085e47b519b426a5c6c7_87_87

See merge request !2031

Fix missing access checks on issue lookup using IssuableFinder

Split from !2024 to partially solve https://gitlab.com/gitlab-org/gitlab-ce/issues/23867

⚠ - Potentially untested
💣 - No test coverage
🚥 - Test coverage of some sort exists (a test failed when error raised)
🚦 - Test coverage of return value (a test failed when nil used)
✅ - Permissions check tested

- [x] ✅ app/controllers/projects/branches_controller.rb:39
  - `before_action :authorize_push_code!` helpes limit/prevent exploitation. Always checks for reporter access so fine with
    confidential issues, issues only visible to team, etc.
- [x] 🚥 app/models/cycle_analytics/summary.rb:9 [`.count`]
- [x] ✅ app/controllers/projects/todos_controller.rb:19

- [x] Potential double render in app/controllers/projects/todos_controller.rb

- https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/2024/diffs#cedccb227af9bfdf88802767cb58d43c2b977439_24_24

See merge request !2030

Fix information disclosure in `Projects::BlobController#update`

It was possible to discover private project names by modifying `from_merge_request`parameter in `Projects::BlobController#update`. This fixes that.

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG.md) entry added
- Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

https://gitlab.com/gitlab-org/gitlab-ce/issues/22869

See merge request !2023

Fix label creation non members

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/23416

See merge request !2006