API for CI Lint

## What does this MR do?
Add API for CI Lint. Can check if `.gitlab-ci.yml` content is valid.

## What are the relevant issue numbers?
Closes #15571 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] API support added
- [x] Documentation
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing

cc @ubudzisz @grzesiek @yorickpeterse

See merge request !5953

Issue #21440: Small fix to curl example for adding member to project

## What does this MR do?
Two lines changed in docs to move the user_id field out of the url and onto the query string 

## Why was this MR needed?
Issue #21440 reported under Issues. The documentation example for adding members to a project had a slight problem. 

## What are the relevant issue numbers?
Closes #21440.

See merge request !6236

Gitlab -> GitLab

## What does this MR do?
Fix GitLab capitalization

See merge request !6235

Lighten color of created icon

#### What does this MR do?
Changes `created` icon color to lighter gray

#### Screenshots (if relevant)
![Screen_Shot_2016-09-06_at_10.25.19_AM](/uploads/6543d0004d817adcbe13cc2b23b6b7bb/Screen_Shot_2016-09-06_at_10.25.19_AM.png)
cc @dimitrieh

See merge request !6230

API: Add the ability to fork to a specific namespace

Browser interface allows forking to an owned grup.
This commit brings API up to speed by providing optional namespace
parameter to fork API. This allows forking to users and groups under
forker's control using their id or unique name.

Fixes #21591 

## 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 [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 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 !6213

Merge branch '18851-commit-text-in-activity-commits-page-etc-has-the-wrong-line-height' into 'master'

Changed `.commit-row-title` `line-height` to `1.35` from `1`

## What does this MR do?

Changes `.commit-row-title` `line-height` to `1.35` from `1`, this is to match the `line-height: 20px;` from before 41c2ea9b.

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

## Why was this MR needed?

Not enough space between commit lines

## What are the relevant issue numbers?

Closes #18851.

## Screenshots (if relevant)

New screenshot below.

## 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)
Closes #18851

See merge request !5996

Reduce intermittent spec failures by making VueJS resource interceptor decrement outstanding resource counts when HTTP response is received

Before the count would be reduced 500 ms after a DOM update tick, which could cause race conditions since the `DatabaseCleaner` could run in the middle of a Rails controller handling the response.

Partial fix to #21197 and other intermittent spec failures.

See merge request !6224

increased checkbox and filter button padding

## What does this MR do?

fixed misalignments as described in https://gitlab.com/gitlab-org/gitlab-ce/issues/19110

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

Not that I know of

## Why was this MR needed?

https://gitlab.com/gitlab-org/gitlab-ce/issues/19110

## Screenshots (if relevant)

![image](/uploads/e7c5ffe78e1a5b67fa0335ba1c231df2/image.png)

![image](/uploads/1591ed872e765da3b5ed071c8872194f/image.png)

## 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
- 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)
- [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)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)


## What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/19110

See merge request !6206

Removed `margin-bottom`

Corrected commit-actions margin

Reverted action margin for a more logical approach

Change "check out, review, and merge locally" URL to SSH by default.

## What does this MR do?

Change the default URL type  in the "Check out, review, and merge locally" pop-up dialog to SSH.

## Why was this MR needed?

The default URL to show on the project screen is the SSH URL, so it makes sense for it to be the default here too. Plus, since most people (hopefully) use SSH keys to avoid typing credentials repeatedly, changing this default means these commands can be pasted into a terminal more easily since no password prompt will get in the way.

## Does this MR meet the acceptance criteria?

- [X] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [n/a ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [n/a] API support added
- Tests
  - [n/a] 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 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 !6211

Updated gitlab_git to 10.6.3

## What does this MR do?

This updated gitlab_git to 10.6.3

## 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)

## What are the relevant issue numbers?

See merge request !6132

Support empty PG database too

cc @rdavila @axil

See merge request !6221

Using the default protocol here (vs HTTP only) is more convenient
when it comes to pasting these commands into a terminal.

This allows us to take advantage of
https://gitlab.com/gitlab-org/gitlab_git/merge_requests/121.