Handle unavailable system info

## What does this MR do?

Handle the case where we can't get system info without blowing up. As this is the first tab in the monitoring section, it's difficult to get to the other tabs if this page throws a 500. Also be more specific about the info we want, so we don't fail on something we don't care about (like `/proc/net/dev`).

## Why was this MR needed?

grsecurity can prevent users from reading `/proc`, which is what Vmstat uses to find CPU and memory info.

## What are the relevant issue numbers?

Closes #21378.

See merge request !5989

Fix wrong Koding link



See merge request !6030

Ensure all javascripts use GitLab install directory as the cookie path.

## What does this MR do?

Fixes #20435 and standardizes all JavaScript-set cookies to use the same root url.

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

Nothing I can think of.  This MR is pretty straight forward.

## Why was this MR needed?

Cookie paths were inconsistent across front-end scripts.  Some would default to '/' and others had no set path and would end up tied to whatever page they were set on.  Also as @connorshea noted, we cannot assume GitLab is installed at '/'.

Before:

![Screen_Shot_2016-08-02_at_10.01.18_AM](/uploads/fa0238e2edf67a8e8ff48f8ee9c8d955/Screen_Shot_2016-08-02_at_10.01.18_AM.png)

After:

![Screen_Shot_2016-08-02_at_10.03.03_AM](/uploads/f1b95936d6f95f2ef1d7db10b5fb09d1/Screen_Shot_2016-08-02_at_10.03.03_AM.png)


## What are the relevant issue numbers?

#20435

## Screenshots (if relevant)

see above

## 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)
- 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 !5627

Adds response mime type to transaction action name when it's not HTML

See merge request !5939

Automatically expand hidden discussions when accessed via a permalink hash (closes #19304)

## What does this MR do?

Addresses "Auto-expand a discussion note when we arrive via anchor" (issue #19304)

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

Let me know if the code is consistent with community standards (not 100% sure about indentation of chained jQuery actions)

I don't think this MR warrants any unit tests or documentation, but let me know if you disagree.  I'll add the requisite CHANGELOG entry upon approval.

## Why was this MR needed?

Currently, if a discussion is accessed via a permalink to an "outdated" diff discussion, the anchor will not bring you to the expected part of the page.

## What are the relevant issue numbers?

#19304 

## 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)
- 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 !5585

Moved two 8.11 changelog entries to 8.12

See merge request !6022

[ci skip]

Reduce number of database queries on builds tab

See merge request !5957

Display project icon from the default branch instead of master

See merge request !5792

Fix markdown link in doc_styleguide.md



See merge request !6021

[ci skip]

This commit makes sure that the project icon is
being read from the default branch instead of
'master'

* remove ref fetch (we do it during creation anyway)
* remove safe_head_commit_sha for diff compare (do not depend on the source branch)
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Use new image for Issue Board page

Replace the Issue Board image with a new one

See merge request !6013

[ci skip]

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

* Add MergeRequestDiff#latest?
* Remove unnecessary variable assignment
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

For Linux with the grsecurity patches applied, paths in `/proc` may not
be readable, so handle those cases and show a message rather than
blowing up.

removed redundant word

## What does this MR do?

fixed a redundant `requests` in file merge_requests.md

See merge request !6007

Add internal API to recovery 2FA

## What does this MR do?

Add an internal API to make SSH 2FA recovery possible. Related to gitlab-org/gitlab-shell!74

See merge request !5510

Add Sentry logging to API calls

## What does this MR do?

This MR adds support for Sentry logging in the API.

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

Since the `Grape::Middleware` doesn't have a `params` method, I had to define one using the Rack Request.

## Why was this MR needed?

We are missing a lot of useful errors in the API causing git push/pull errors

## What are the relevant issue numbers?

#21043

See merge request !5882

changes from using size to count and caching it to get the number of members in a group

- [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
  - [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)
Closes #20909

See merge request !5935

Does not halt the GitHub import process when an error occurs

## What are the relevant issue numbers?

Fixes #20385 

https://gitlab.com/gitlab-org/gitlab-ce/issues/20149

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [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 !5763

Restore get_id in ExtractsPath

fixes #21334

`Addressable::URI.normalize_component()` around `get_id` which was introduced by 68cea38e and removed in !5878 is still intentionally omitted. Using `normalize_component()` instead of `unescape()` left `%` as is but still broke e.g. spaces (which were replaced by `%20`).

See merge request !5974

Use gitlab-workhorse 0.7.11

Versions 0.7.9 and 0.7.10 crash on previously valid 'authBackend'
settings.

I don't know how many people are affected by this, 'normal' Omnibus
installations are not. (If they were gitlab.com would have stopped
working :) ). Still this is something we should not ship.
Unfortunately 8-11-stable uses 0.7.10 (but 8.11.0 does not). So I
think we need to put this in the next 8.11 patch release.

See merge request !5983

expose 'only_allow_merge_if_build_succeeds' project setting in the API

## What does this MR do?
Adds the 'only_allow_merge_if_build_succeeds' project setting in the API.

## Are there points in the code the reviewer needs to double check?
No, but maybe this code is not enough for ACLs or the like.

## Why was this MR needed?
Because that's a very useful setting to change via automation (through the API)

## What are the relevant issue numbers?

Closes #21085, closes https://gitlab.com/gitlab-org/gitlab-ce/issues/20088.

## Screenshots (if relevant)

## 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
  - [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 !5930

api: expose web_url for project entities

## What does this MR do?

Adds a `web_url` field to project snippet, issues, and merge request API returned objects.

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

Tests. Are they sufficient? (I'm working on getting them to pass.)

## Why was this MR needed?

Creating the URL for an MR or issue from the MR is tedious in API libraries; it's easy for Gitlab to just provide it.

## What are the relevant issue numbers?

N/A

## Screenshots (if relevant)

N/A

## 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
  - [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 !5631

Closes #21043

Update merge_requests.md with a simpler way to check out a merge request

## What does this MR do?

This MR updates `merge_requests.md` with a simpler way to check out a merge request 

The previous way was put under the "By modifying `.git/config` for a given repository" section. The disadvantage of the old way is that one has to modify `.git/config` for each repository that one uses. The new way was put under the "By adding a git alias" section. One has to create this git alias once, and then it will work from any repository, without having to modify `.git/config` over and over again.

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

One should double check that the link provided by the "Check out branch" button in a MR, i.e. https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/workflow/merge_requests.md#checkout-merge-requests-locally, still works. I think it will, since I didn't modify the "Checkout merge requests locally" section name.

## Why was this MR needed?

This MR was needed because the old way of checking out a merge request locally requires to modify `.git/config` in all repositories that one has on a computer, which is a tedious task. The new way just requires adding a simple git alias, once. And the `git mr` command then works for all repositories.

## What are the relevant issue numbers?

I haven't created an issue for this.

## Screenshots (if relevant)

N/A

## 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)
- [ ] API support added (N/A)
- Tests
  - [ ] Added for this feature/bug (N/A)
  - [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 !5944

Api project hook wiki page events

## What does this MR do?

Updates project hook API for wiki page events. Also updates docs and tests for forgotten hook fields.

See merge request !5969