Fix issue with overlap of sidebar links.
Thanks @iamphill for the help with this one.

cc @iamphill @alfredo1 @dzaporozhets @rymai
See merge request !3043
Properly check for a pre-existing error in `User#namespace_uniq`
Rails adds an empty error to the Errors object even if you just call
`#[]` on it:
```
[1] pry(main)> u = User.last
[2] pry(main)> u.errors.keys
=> []
[3] pry(main)> u.errors[:username].present?
=> false
[4] pry(main)> u.errors.keys
=> [:username]
```
See merge request !3017
Don't show any "2FA required" message if it's not actually required
Prior, if the user had enabled and then disabled 2FA, they would be
shown a "You must enable Two-factor Authentication for your account."
message when going back to re-activate it, even if 2FA enforcement was
disabled.
See merge request !3014
Changed # to ! on merge requests on activity view
Closes#9082

See merge request !2938
Batch size >1000 does not pay off
We did a small experiment to see how a full scan of the Redis keys on
gitlab.com speeds up as we increase the batch size. The values on the
right are time in seconds for a full scan (no delete operations).
```
count: 10); 284.500529021
count: 100); 86.21216934
count: 1_000); 60.931676195
count: 10_000); 60.96355610
count: 100_000); 62.378172541
```
It looks like 1,000 is a good number.
See merge request !2970
Add commit message to slack script
Ass suggested by @rdavila, this adds the current commit message as of HEAD to the slack script.
See merge request !3027
Rails adds an empty error to the Errors object even if you just call
`#[]` on it:
```
[1] pry(main)> u = User.last
[2] pry(main)> u.errors.keys
=> []
[3] pry(main)> u.errors[:username].present?
=> false
[4] pry(main)> u.errors.keys
=> [:username]
```
Fixes padding loss after editing a diff comment
Also applies .timeago() to comment datetimes when diff page is entered directly.
Also fixes the vertical position of the comment count icon.
See merge request !3012
Prior, if the user had enabled and then disabled 2FA, they would be
shown a "You must enable Two-factor Authentication for your account."
message when going back to re-activate it, even if 2FA enforcement was
disabled.
Prior, if the user enabled 2FA, then disabled it and came back some time
after the grace period expired, they would be forced to enable 2FA
immediately.
Fix for project paths ending in .wiki
This prevents `Git operation was rejected by pre-receive hook` when
an actual project ending with .wiki is thought to be a wiki by the
`Internal` API.
Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/13742
See merge request !2960
Improve implementation to check read access to forks and add pagination.
Fixes#13648
The following optimizations where made:
- Pagination was added.
- Code to check for read permissions to forks was optimized, in the past we were doing too many queries for each project.
See merge request !2991
Removed NGProgress
In an effort to get the JS file size down, i've removed NGProgress and replaced with TurboLinks own loading indicator
Ref #13820

See merge request !3004
Changed too many changes buttons to white
Closes#13751

See merge request !3002