Reduce SQL query counts in IssueReferenceFilter

## What does this MR do?

This MR adds a preparation phase for reference filters that allows them to prepare/create data structures used while iterating over HTML nodes. In this particular case the preparation phase is used for issue references to greatly cut down the amount of queries executed to get projects/issues for Markdown references.

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

No.

## Why was this MR needed?

Rendering Markdown containing issue references would run at most two queries for every issue reference: one to get the project and one to get the issue from said project. When rendering Markdown with lots of issue references this would result in _a lot_ of queries being executed.

## What are the relevant issue numbers?

#18042

See merge request !4410

Implements TemplateDropdown class to create custom template dropdowns

## What does this MR do?
Refactorize template dropdowns. This MR creates a base TemplateSelector class so it can be reused for multiple types of templates.

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry 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
- [ ] 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 you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4697

Use gitlab_git 10.1.4

Towards https://gitlab.com/gitlab-org/gitlab-ce/issues/18690,
following https://gitlab.com/gitlab-org/gitlab_git/merge_requests/87 .

See merge request !4706

Fix images in emails

Closes #18474. The confirmation email is actually the only one that uses the `image_tag` helper at the moment, but this will work for all of them:
```shell
$ ag image_tag -G mailer
app/views/layouts/devise_mailer.html.haml
13:              = image_tag('mailers/gitlab_header_logo.png', id: 'logo', alt: 'GitLab Wordmark')
24:                  = image_tag('mailers/gitlab_tanuki_2x.png', alt: 'GitLab Logo')
```

See merge request !4705

Banzai::Filter::ExternalLinkFilter use XPath

See merge request !4702

Update migration_style_guide.md with new details

See merge request !4693

Lighten each logo path color instead of white

## What does this MR do?
Changes highlight/loading colors of tanuki from white to a lighter version of each path color

## Why was this MR needed?
Since the logo is no longer on the dark sidebar, the highlight color was getting lost against the light gray background

## What are the relevant issue numbers?
Closes #18521 

## Screenshots (if relevant)
![logo](/uploads/3743925862fa8e17d2fec426f7e4c853/logo.gif)

cc @jschatz1 @lbennett @dzaporozhets 

See merge request !4690

Improve pipeline status in case that pipeline has no jobs

## What does this MR do?

This MR resolves problem with pipeline status when there are no build in pipeline.

This can happen when builds were skipped - for example - by using `only`/`except` keyword in `.gitlab-ci.yml`.

## What are the relevant issue numbers?

Closes #17977

See merge request !4403

Turn Group#owners into a has_many association

## What does this MR do?

This turns the regular method `Group#owners` into a `has_many` association.

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

As far as I can tell there's no way to do this without using an intermediate association, but perhaps I'm missing something. The reason an intermediate association is needed is because the supplied Proc is applied to the _final_ association (the one returning users), this means that when using a single `has_many` you can't filter out any intermediate rows (e.g. group members).

## Why was this MR needed?

This code being a regular method would prevent eager loading of the owners of a Group, turning it into a `has_many` association resolves this problem. This was discovered in !4410.

## What are the relevant issue numbers?

None.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [x] ~~API support added~~
- [ ] Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] 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 you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4676

Make project_id nullable

See merge request !4701

See merge request !4707

Update CHANGELOG

[ci skip]

See merge request !4695

Revert "Merge branch '18047-event-item-links-dont-look-like-links' into 'master'"

## What does this MR do?

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

## Why was this MR needed?

## What are the relevant issue numbers?

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry 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 [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4692

Pinned sidebar navigation option

## What does this MR do?

Gives the ability to pin the sidebar navigation. Pinning is only possible on screens with above `lg` which is `1200px` if not it reverts to being hidden by default.

## What are the relevant issue numbers?

Closes #18542 

## Screenshots (if relevant)

### Un-pinned

![Screen_Shot_2016-06-15_at_17.29.08](/uploads/82b7495df6ea46a2334a7c25d03b019b/Screen_Shot_2016-06-15_at_17.29.08.png)

### Pinned

![Screen_Shot_2016-06-15_at_17.29.41](/uploads/3eb381be807985d0a9583f000cb802f9/Screen_Shot_2016-06-15_at_17.29.41.png)

See merge request !4683

Improve usability for prioritized labels

## What does this MR do?
- Adds an icon next to prioritized label rows serving as a hint to the user that the labels can be sorted by dragging them.
- Adds description about prioritized labels.
- Restores empty message when removing all prioritized labels.

## Screenshots (if relevant)

![labels](/uploads/1da16c4c54a894fa45ccc47e3a5bdf7a/labels.gif)

Closes #18575 

See merge request !4652

Fix long commit message scroll issue.

Fixes horizontal scrollbar for long commit description.

## Before
![before_](/uploads/d261e26044d8ab451bc7768b16316253/before_.png)

## After
![after](/uploads/f27227a77d25d80b797e3ffc916d1957/after.png)

See merge request !4643

Fixed notes action buttons on mobile

## What does this MR do?

Fixes the mobile screen size styling for notes action buttons. It ensures there is space between icons and forces parts of the notes header to stack

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

Stacking? 

## Why was this MR needed?

UX

## What are the relevant issue numbers?

Closes #18434.

## Screenshots (if relevant)

![Screen_Shot_2016-06-13_at_17.52.09](/uploads/18849fdfc4fcbf7b67fc66633bbac129/Screen_Shot_2016-06-13_at_17.52.09.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry 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 [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4631

Fix clicking of find and download areas on file page

## What does this MR do?

Fixes the stacking context of the file page so the find and download areas can be clicked

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

Ney

## Why was this MR needed?

We wanna click them. :(

## What are the relevant issue numbers?

Closes #18340.

## Screenshots (if relevant)

![Screen_Shot_2016-06-09_at_18.46.05](/uploads/1650a2fb1b9119ad1e27badf31f49340/Screen_Shot_2016-06-09_at_18.46.05.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry 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 [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4574

Updated CHANGELOG

Removed CHANGELOG entry

added hover state to top nav links

## What does this MR do?

Adds hover state to top nav links.

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

Ney.

## Why was this MR needed?

UX.

## What are the relevant issue numbers?

Closes #18301.

## Screenshots (if relevant)

![Screen_Shot_2016-06-07_at_23.23.45](/uploads/dac8ed99eca99fbcccbd98028e947ee1/Screen_Shot_2016-06-07_at_23.23.45.png)

See merge request !4521

Replace raphael-rails with raphael.js and split it from the rest of the JS

## What does this MR do?

Removes raphael.js and its related libraries from the default JS bundle.

It also removes raphael-rails because the gem is unmaintained and – for whatever reason – didn't want to cooperate with the way I was trying to require it.

This brings the default (compressed and minified) application.js from 354KB after the d3 MR (!4394) down to 324KB.

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

That tests pass and that there aren't errors on any pages (especially the Network page).

## Why was this MR needed?

It's only used on the Network page and was using way too much bandwidth for just one page.

## What are the relevant issue numbers?

#14372 #13165 

Follow-up to !4394 and !4516.

cc: @jschatz1 

See merge request !4519

Show categorised search queries in the search autocomplete

Fixes #5885 

It works in 3 categories, Dashboard, Groups and Project.

## Dashboard context
![for-dashboard](/uploads/3a59f6ec008a972495597c8f2691c385/for-dashboard.png)

## Group context
![for-group](/uploads/f7aa413d56330a1d9b2e5562f95badf7/for-group.png)

## Project context
![for-project](/uploads/dabe04cf8758a056cf7b03da001ffd91/for-project.png)


## Screencast
![category-search-dropdown](/uploads/4d9513dcd6ccb6e24adefdf65f9bc778/category-search-dropdown.gif)



See merge request !4499

Due date can be removed from milestones

## What does this MR do?

Adds a button to milestone form to allow user to remove due date 

## What are the relevant issue numbers?

Closes #15063 

## Screenshots (if relevant)

![Screen_Shot_2016-06-02_at_08.32.03](/uploads/8bd4446abde745dd5b1e140a887ec694/Screen_Shot_2016-06-02_at_08.32.03.png)

See merge request !4428

Fixed issue with bold in issuable sidebar

## What does this MR do?

~~The sidebar contained both normal font weight & bold font weight, so this standardises them to bold.~~

After looking at the designs, i've updated the font weights & colors throughout the sidebar to correctly match them

## Screenshots (if relevant)

![Screen_Shot_2016-06-02_at_11.03.40](/uploads/0a3eb6a67ce5722c77f6adf2fe883017/Screen_Shot_2016-06-02_at_11.03.40.png)


See merge request !4398

Add shortcut to copy file content hash link

## What does this MR do?

* Allows for multiple shortcut handlers to be initialised
* Adds `y` shortcut to file pages to copy permalink URL.

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

Ney.

## Why was this MR needed?

UX

## What are the relevant issue numbers?

Closes #14470.

## Screenshots (if relevant)

![y-shortcut](/uploads/b81feb26d8e0d7d4996c4afa29f385d7/y-shortcut.gif)

See merge request !4496

New issue shortcut doesnt work on some pages

## What does this MR do?

1. Slightly tidies dispatcher switch case by utilising 'fall through' cases.
2. Adds shortcuts to project pipelines, milestones, builds and forks pages

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

I have a feeling that these may have been missed out of the case statements on purpose?

## Why was this MR needed?

Possible UX issue highlighted in #17929.

## What are the relevant issue numbers?

Closes #17929.

Closes #12616. (dup)

Closes #18123. (dup)

Closes #13688. (dup)

## Screenshots (if relevant)

See merge request !4393

Updated CHANGELOG

Removed CHANGELOG entry

Updated commits UI

Closes #14633 

See merge request !4271

Get rid of Gitlab::ShellEnv

Remove obsolete code we once needed for Grack and satellites.

See merge request !4673

Resolve "Change admin navigation to match new UI"

## What does this MR do?
Moves admin navigation to layout nav to match Project, Groups, and Profile navigation

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

## Why was this MR needed?

## What are the relevant issue numbers?
Closes #18338

## Screenshots (if relevant)
![Screen_Shot_2016-06-14_at_10.26.40_AM](/uploads/f0b8c8b259da16d929be2b36e8eeafb8/Screen_Shot_2016-06-14_at_10.26.40_AM.png)
![Screen_Shot_2016-06-14_at_10.26.44_AM](/uploads/07d9ece2063dfcfec1f0f2647d8ee782/Screen_Shot_2016-06-14_at_10.26.44_AM.png)
## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry 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 [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4650

Prevent default disabled buttons and links.

## What does this MR do?
Prevents default action for disabled buttons and links. If the element has `.btn` and `.disabled` at the same time, its default action will be prevented.

## Are there points in the code the reviewer needs to double check?
Yes. Is there a better way to do that?

## Why was this MR needed?
Right now we can click disabled links and it cause some troubles like in #18079.

## What are the relevant issue numbers?
Fixes #18079

## Screenshots (if relevant)
![disabled-click](/uploads/48b58ce130f843e530e62632bcc27436/disabled-click.gif)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [x] Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [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 you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4658

Show number of processed MRs in milestone page

closes #14025 

![Screen_Shot_2016-05-02_at_6.20.34_PM](/uploads/9208e58c0e0c77133bd73332ee3b3342/Screen_Shot_2016-05-02_at_6.20.34_PM.png)

See merge request !4006

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Add index on `requested_at` to the `members` table

See merge request !4679

Fixed issue with MR buttons being in a group

## What does this MR do?

Fixes design issue with the buttons in the merge request widget

## Screenshots (if relevant)

![Screen_Shot_2016-06-09_at_14.13.32](/uploads/44ac4175f5a97a8d7baf97be6eebc684/Screen_Shot_2016-06-09_at_14.13.32.png)


See merge request !4562

Check if the Users table has exactly one user limiting the whole set

## What does this MR do?

Limit the query set so about a full scan for all the rows on the users table (only scan to records)

#18225 

See merge request !4492