Removed sorted text from dropdowns

Closes#12796
cc @creamzy @jschatz1
See merge request !2635
Makes ol margin big enough for 3 digits.
Fixes#7960

See merge request !2608
By simply loading the first event from the already sorted set we save
ourselves extra (slow) queries just to get the latest update timestamp.
This removes the need for Event.latest_update_time and significantly
reduces the time needed to build an Atom feed.
Fixesgitlab-org/gitlab-ce#12415
The pattern in the `::reference_pattern` class method in the
ExternalIssue model does not match all valid forms of JIRA project
names. I have updated the regex to match JIRA project names with numbers
and underscores. More information on valid JIRA project names can be
found here:
https://confluence.atlassian.com/jira/changing-the-project-key-format-192534.html
* The first character must be a letter,
* All letters used in the project key must be from the Modern Roman Alphabet and upper case, and
* Only letters, numbers or the underscore character can be used.
Fixes: Search box in Group Members view is too small for placeholder in Chrome
Fixes#2498

See merge request !2609
Save button on app settings now btn-save
Some save buttons where `btn-primary` where throughout the application these usually are `btn-save`.
Before (Application settings)

After

See merge request !2612
Track project import failure
Fixes#12512
This also help us on identify why the import process is returning the wrong status when the project was successfully imported. Like mentioned in the issue #12450
See merge request !2538
Make the `/groups` route behave as expected
The route is supposed to redirect the Groups#index request based on
whether or not a user was logged in. If they are, we redirect them to
their groups dashboard; if they're not, we redirect them to the public
Explore page.
But due to overly aggressive `before_action`s that weren't excluding (or including) the
`index` action, the request always resulted in a 404, whether a user was
logged in or not.
Closes#12660
See merge request !2580