Add container registry support
Tasks:
- [x] Merge docker/distribution authentication service: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/3787
- [x] Implement Docker Registry API
- [x] Show a list of docker images in GitLab
- [x] Remove registry repository on project deletion
- [x] Support project rename, move and namespace rename
- [x] Use token when connecting the registry
- [x] Allow to delete images from GitLab
- [x] Support pushing from GitLab CI (gitlab-ci-token / $CI_BUILD_TOKEN)
- [x] Support GitLab Runner pulling for public repositories
- [ ] Support GitLab Runner pulling for private repositories
- [x] Add tests for Docker Registry API
- [x] Add tests for a views
- [x] Make texts nicer
- [x] Implement a backup support
- [ ] Create administration documentation https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4141
- [ ] Create user documentation
See merge request !4040
Update build log incrementally
Proof of concept implementation of incremental sending of build log to browser.
cc @jschatz1 @vsizov @grzesiek @tmaczukin
See merge request !3737
Reuse runners edit form in admin and project area
Reuse runners edit form in admin and project area.

See merge request !4094
Improve documentation and web test for web hooks
Tips and documentation of actual hook behavior. Improved user feedback
when testing hooks via the web UI.
See merge request !4015
We send a state of ansi2html to client, client needs to send this state back.
The state describes the configuration of generator and position within trace.
Backported minimal safewebhook implementation to GitLab CE
This brings a minimal implementation for gitlab-org/gitlab-ce#13478
backported from EE (gitlab-org/gitlab-ee!334).
Also added UI to configure Secret Token
Fixes#15365.
See merge request !3940
Load the "New Branch" button asynchronously
Here's how it looks like for logged in users:

And here it is for anonymous users (or when a new branch can't be created by a logged in user):

See merge request !3855
This button depends on Issue#can_be_worked_on? which in turn depends on
Issue#related_branches. By rendering this button asynchronously we can
finally remove all usages of Issue#related_branches and
Issue#referenced_merge_requests from the issues "show" page.
Always read diff_view setting from the cookie
Prior, when the user had their view set to "parallel" and then visited a
merge request's changes tab _without_ passing the `view` parameter via
query string, the view would be parallel but the `Notes` class was
always instantiated with the default value from `diff_view` ("inline"),
resulting in broken markup when the form to add a line note was
dynamically inserted.
The cookie is set whenever the view is changed, so this value should
always be up-to-date.
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/14557 and https://gitlab.com/gitlab-org/gitlab-ce/issues/15285
See merge request !3732
Fixes text color on labels in sidebar
Previously the labels in the sidebar would just have `#FFF` text color which could cause problems with a light background color.
With this, the text color comes from the JSON.
See merge request !3846