Add basic documentation for build artifacts

/cc @axil @ayufan 

See merge request !2511

Add documentation on restarting GitLab

This will save as time from writing the same commands
over and over again.

See merge request !2510

[ci skip]

[ci skip]

Do not use progress bar when downloading build artifacts

Closes #12491

See merge request !2531

Remove execution permissions from font assets

[ci skip]

See merge request !2082

Init script changes for gitlab-workhorse in 8.4

Goes with https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/31

Also bumps gitlab-workhorse to 0.6.1.

[ci skip]

See merge request !2529

Fix import of GitHub's wiki when the repository has not been created

Fixes #12503 

See merge request !2533

Closes #12491

Instrument Gitlab::Git::Repository



See merge request !2528

Added cache:key to .gitlab-ci.yml allowing to fine tune the caching

The `cache:key` allows you to define the affinity mask of caching, allowing to have single cache for all jobs, or cache per-job, or per-branch, or any other way you would need:

1. Cache per-build for all branches:

```
cache:
    key: "$CI_BUILD_NAME"
    untracked: true
```

2. Cache per-branch for all jobs:

```
cache:
    key: "$CI_BUILD_REF"
    untracked: true
```



/cc @DouweM @grzesiek @axil


See merge request !2436

This adds instrumentation for the instance methods of
Gitlab::Git::Repository.

Implement new UI for pagination

Fixes #6063 ![Screenshot_2016-01-20_09.38.59](/uploads/f50d333bdb6cb9683848fb0a874241ef/Screenshot_2016-01-20_09.38.59.png)


See merge request !2517

Fix term height so text overflap does not happen.

Fixes #12449 

Height was set on the `.term`. It made the text overlap. 

See merge request !2518

Creator should be added as a master of the project on creation

Fixes #4222 

This also enable a project creator to add themselves as a master of the
project for existing repositories that were created in the meanwhile
that they don't appear as members.

See merge request !2520

[ci skip]

[ci skip]

Adds disabled comment field and disabled avatar.

Fixes #3540

![Screen_Shot_2016-01-20_at_12.13.29_AM](/uploads/673fb783e9aeae441df9c40bfe29ac1b/Screen_Shot_2016-01-20_at_12.13.29_AM.png)


See merge request !2508

Added documentation for GitLab Metrics

This adds documentation for the metrics code I recently added.

Two notes:

* I'm referring to this feature as "GitLab Metrics" everywhere simply
  because the code resides in the `Gitlab::Metrics` namespace. A
  different name is fine, though I think just "Metrics" might be a bit
  too abstract.
* Grafana isn't covered since it's fairly straight-forward to setup
  (there's nothing really special we can cover). I think we _should_
  cover it once we start shipping it with Omnibus.

I assigned @axil since he's our technical writer/documentation guru,
feel free to re-assign if needed.

cc @sytses @axil @dzaporozhets @JobV 

See merge request !2484

Fix cross projects detection when importing GitHub pull requests

Fixes #12456

See merge request !2523

[ci skip]

This also enable a project creator to add themselves as a master of the
project.

[ci skip]

Add syntax highlighting to diff view

Closes #3945 

See merge request !2109

Mention required Ruby version

Closes #12446

See merge request !2524

[ci skip]

Add note about minimum GitLab CI version

Documentation update: To use variables in `.gitlab-ci.yml` it's not enough to update the GitLab Runner, a minimum version of GitLab CI is needed as well.

See merge request !2514