Add some polish to CI integration

Check the list of commits to see what I changed.

cc @dzaporozhets

@rspeicher I'd love to get this into 8.1, since it's mostly refactoring/tweaking of stuff that was _introduced_ in 8.1.

Fixes #2645.

See merge request !1641

- Add page titles to CI settings.
- Fix CI admin navigation.
- Remove duplicated scope.
- Use monospace font for commit sha.
- Add page title and header title to build page.
- Proper authorization for cancel/retry builds.
- Use gitlab pagination theme for builds and group members.
- Don't paginate builds widget on build page.
- Add badges to commit page Changes/Builds tabs.
- Add "Builds" to commit Builds tab page title.
- Add and use Ci::Build#retryable? method.
- Add CI::Build#retried? method.
- Allow all failed commit builds to be retried.
- Proper authorization for cancel/retry all builds.
- Remove unused param.
- Use time_ago_with_tooltip where appropriate.
- Tweak builds index text
- Remove duplication between builds/build and commit_statuses/commit_status.
- Use POST rather than GET for canceling and retrying builds.
- Remove redundant URL helpers.
- Add build ID to build page.
- Link branch name on build page.
- Move commit/:sha/ci to commit/:sha/builds.

Allow groups to appear in the search results if the group owner allows it

https://dev.gitlab.org/gitlab/gitlabhq/issues/2565

See merge request !1751

update example of regex for pytest-cov



See merge request !1745

fixed typo in installation manual

Add Facebook authentication

See merge request !1740

Replace all usages of `git` command with configurable binary path

Closes #3311

See merge request !1742

Only redirect to homepage url when its not the root url

It was possible to create an infi redirect when the user set up the
`home_page_url` to redirect to the main URL of the gitlab instance.

This fix makes sure this redirect is not possible.

Fixes #1020 

/cc @dblessing 

See merge request !1703

Improvements to profile page UI

* add separator between tabs
* show project avatars
* fix tooltip offset on user calendar
* remove gray hover for tabs
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

For #3042

See merge request !1747

* add separator between tabs
* show project avatars
* fix tooltip offset on user calendar
* remove gray hover for tabs
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Improve performance of creating projects



See merge request !1650

Remove duplicate orders

This changes the default order from `created_at DESC, id DESC` to just `id DESC` as this achieves the same results without the overhead of having to sort data twice (we've seen queries go from 200ms to just a few ms by removing the double sort).

cc @jacobvosmaer @dzaporozhets @rspeicher @DouweM 

See merge request !1735

Bump stamp to ~> 0.6.0

Closes #2801

See merge request !1732

Closes #3311

[ci skip]

Closes #2801

Spread out runner contacted_at updates

This is meant to prevent having too many concurrent UPDATE requests
caused by runners checking in.

See merge request !1722

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

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

Fix clipboard button overflow
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !1739

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

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

Cleanup stuck CI builds

Fixes #3143

/cc @dzaporozhets @jacobvosmaer 

See merge request !1655

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

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

Extend yml syntax for only and except to support specifying repository path

This allows to limit execution of jobs to specific repository.

For example:
```yaml
job:
  only:
    - branches@gitlab-org/gitlab-ce
  except:
    - master@gitlab-org/gitlab-ce
```

The above will run `job` for all branches on `gitlab-org/gitlab-ce`, except master.

@dzaporozhets @JobV @vsizov Please review.


See merge request !1720