Display target branch on MR list when it is different from project's default
Fixes#3072
The screenshot below shows both previous and current UI state:

First merge request has default branch as a target, second one has non default branch as target.
See merge request !1741
Merge button has color from CI status
This MR closes#3313
I'am not realy sure about the color for the skipped status (red)...
UI changes:




See merge request !1761
Sherlock will be a new GitLab specific tool for measuring the
performance of Rails requests (and SideKiq jobs at some point). Some of
the things that are currently tracked:
* SQL queries along with their timings, backtraces and query plans
(using "EXPLAIN ANALYZE" for PostgreSQL and regular "EXPLAIN" for
MySQL)
* Timings of application files (including views) on a per line basis
* Some meta data such as the request method, path, total duration, etc
More tracking (e.g. Rugged or gitlab-shell timings) might be added in
the future.
Sherlock will replace any existing tools we have used so far (e.g.
active_record_query_trace and rack-mini-profiler), hence the
corresponding Gems have been removed from the Gemfile.
Sherlock can be enabled by starting Rails as following:
ENABLE_SHERLOCK=1 bundle exec rails s
Recorded transactions can be found at `/sherlock/transactions`.
Fix bug where manually merged branches in a MR would end up with an empty diff
This bug manifested in 8.1 with the refactoring of `RefreshService`. Here's what happens:
1. User create a new branch `foo`.
2. User creates a merge request for `foo`.
3. User merges `foo` into `master` by hand.
4. `RefreshService` reloads the merge request. Since `master` is equivalent to `foo`, this results in an empty diff.
5. `RefreshService` then closes the MR.
This wasn't an issue when you use the normal "Accept Merge Request" flow because the act of clicking the button closes the merge request, so step 4 never happens.
Closes#3314
See merge request !1758
Enable shared runners for all new projects
This adds Admin Setting option to enable shared runners for all new projects, and by default it is set to true.
/cc @dzaporozhets @sytses
See merge request !1738