Small UI improvements to merge request page

Make gray block under tabs identical height. Also same height have blocks on pages like `Groups` etc. So this improvement is targeted for consistency in UI too
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fixes internal issues 

* https://dev.gitlab.org/gitlab/gitlabhq/issues/2591
* https://dev.gitlab.org/gitlab/gitlabhq/issues/2592

cc @DouweM 


See merge request !1759

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

fix line order in installation docs

ugly outlines removed form sidebar

form-control class added to select box

Only have one link in emails to make clicking it easier.



See merge request !1937

Add CI permissions and api links to README



See merge request !1756

Make migrations reversible



See merge request !1753

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.

9722 fix alignment of event items and its children

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

Otherwise text will flow under the "timeago" element.
The original value was 80px (see commit 8b0906c8), but a value of 174px
makes more sense. (see event-title `calc` function).

update example of regex for pytest-cov



See merge request !1745

fixed typo in installation manual

Prevent the second, third, ... rows from having a different indentation
than the first commit row.

Adding the extra "15px padding" to the event item prevents this.
Having a 15px margin on the avatar only doesn't prevent this from
happening.

Add Facebook authentication

See merge request !1740

Try to avoid alignment issues as well.

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

Closes #3311

See merge request !1742

On a tablet in portrait mode with a width of 768px the event-title isn't
aligned properly when the title contains a long string. This also
happens when resizing your browser viewport on a desktop.

Example string:
Administrator pushed new branch feature-branch-with-a-very-long-name at
Gitlab Org / Gitlab Test

In the UI it would look like the example below:

----------
|        |
| AVATAR |                                                                          less than a minute ago
|        |
----------
           Administrator pushed new branch feature-branch-with-a-very-long-name at...

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: NDmitriy 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: NDmitriy 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