Document when Docker Registry manifest v1 support was added

## What does this MR do?

Document when Docker Registery manifest v1 support was added

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

Is this the best way to document this? We never documented support for v2 or which docker versions we support overall.

## Why was this MR needed?

We made a change and it wasn't documented. Also, it's good to document which docker versions we support.

## What are the relevant issue numbers?

!4669

## Screenshots (if relevant)


See merge request !5378

Clarify artifacts:name default value

## What does this MR do?

Add the default artifact name (`artifacts`) to documentation.

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

## Why was this MR needed?

We didn't document the default artifact name.

## What are the relevant issue numbers?

## Screenshots (if relevant)


See merge request !5377

Revert Content Security Policy

The secure-only cookies setting was causing an issue where the session was
constantly being lost in the development environment.

Revert "Merge branch 'csp-basics' into 'master'"

This reverts commit 9065f9c5, reversing
changes made to f0b446e5.

---

Revert "Merge branch 'remove-csp-sentry-reporting' into 'master'"

This reverts commit 79b02e40, reversing
changes made to f2cd21e8.

See merge request !5381

This reverts commit 9065f9c5, reversing
changes made to f0b446e5.

This reverts commit 79b02e40, reversing
changes made to f2cd21e8.

Remove flaky diff note tests for now

These will be replaced with better, more exhaustive specs by @lbennett based on the conversation in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5262.

See merge request !5379

Prevent toggling sidebar when clipboard icon clicked.

Prevents sidebar being toggle when copy to clipboard icon clicked.

Fixes #19399 

![sidebar-toggle](/uploads/e4e8dfe9ff2546464269242b5f3e34b1/sidebar-toggle.gif)

See merge request !5326

Refactor user authorization check for a single project to avoid querying all user projects

See merge request !5102

Added the ability to block sign ups using a domain blacklist.

As part of this MR, I restructured the Application Settings form to separate **Sign up** related settings from **Sign in** related settings and make everything cleaner and easier to read.

Fixes #19749 

Related to #5573

See merge request !5259

Speed improvement for builds without DB

Only fetch the images which we are going to use. Speeds up the builds by about 30-45 seconds.

/cc @ayufan 

See merge request !4994

Currently, even when searching for all authorized issues of *one* project, we run the
`Users#authorized_projects` query (which can be rather slow). This update checks if
we are handling issues of just one project and does the authorization check locally.
It does have the downside of basically repeating the logic of `Users#authorized_projects`
on `Project#authorized_for_user`.

Warn on failure

## What does this MR do?

Adds styling and HTML for a `success_with_warnings` status in the MR widget. Unfinished as it needs some plumbing in the relevant CI controllers and models.

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

Not at the moment, though I think I'll probably need help getting this to work in the backend.

## What are the relevant issue numbers?

#17669 

## Screenshots (if relevant)

![Screen_Shot_2016-06-29_at_12.02.49_PM](/uploads/af4a915689633fe028f44bb34ae7a5b1/Screen_Shot_2016-06-29_at_12.02.49_PM.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)

cc: @ayufan 

See merge request !5004

Merge branch '14284-allow-all-deploy-keys-to-be-retrieved-via-api-regardless-of-project-affiliation' into 'master'

Add /deploy_keys API to retrieve all deploy keys regardless of project affiliation

## What does this MR do?

Add /deploy_keys API to retrieve all deploy keys regardless of project affiliation

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

Is documentation clear?

## Why was this MR needed?

User request

## What are the relevant issue numbers?

#14284

See merge request !4426

Fix side by side comment widget

Fixes comment button for empty lines in side by side diff view.

Fixes #19824 
Fixes #19957

See merge request !5262

Also, in favour of consistency, deprecate `/projects/:id/keys/...` routes in favour of
`/projects/:id/deploy_keys/...`

Add link to profile to commit avatar

## What does this MR do?

- links to user profiles to the avatars on commits page
- tooltips to the avatars on commits page

side effect:

- links to user profiles to the avatars on pipelines page
- tooltips to the avatars on pipelines page
- tooltips to the avatars on activity page
- mailto links to the avatars on activity page for non-registered users

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

Nope.

## Why was this MR needed?

There were no links nor Zeldas.

## What are the relevant issue numbers?

fixes #19644 


See merge request !5163

Added checks for migration downtime

This adds a set of checks that check/list which migrations require downtime (or not). It also comes with a CI task that fails should a migration not be tagged properly.

Fixes #14545

See merge request !4911

Enable Style/MultilineTernaryOperator rubocop cop

Avoid multi-line ?: (the ternary operator). Use if/unless instead.

See #17478

See merge request !4356

Allow slack service to send messages on different channels

closes #8110 

## Allow slack service to send messages on different channels  

![new_slack_service](/uploads/87de0bd6b02a4f7853358676b5e74dff/new_slack_service.png)

## 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 !5124

Fix two small problems on how we handle manual actions

## What does this MR do?
Fixes two small problems in how we handle manual actions:
- On environments page we show a `Play` for the same action that is lately deployed, we should show other actions only
- When we process a pipeline that have only a manual action in a stage, the pipeline will stop being processed.

- 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 !5366