Add ability to see and sort on vote count from Issues and MR lists
Fixes#3763
* Sort options

* Most popular

* Least popular

See merge request !2781
Prevents floated button group on issues view
Issue #13359

See merge request !2826
This ensures that _all_ caches (including any caches normally only
flushed under certain conditions) are flushed whenever a project is
removed. Because cache keys are based on project namespaces (excluding
IDs) not doing so could result in a newly created project re-using old
caches (if the project was re-created using the same name).
This ensures the caches for Repository#empty? and
Repository#has_visible_content? are flushed after a repository has been
imported or forked.
Fixesgitlab-org/gitlab-ce#13505
fix table in doc/ci/variables/README.md
The table was missing a column separator, causing GitLab to render the
markdown incorrectly.
[ci skip]
See merge request !2840
Sidebar fixes
Fixes#13215
* when editing a dropdown, but not changing anything you end up in an ugly state
* the hover-over state for the subscribe and other buttons are veeery subtle
* the collapse button needs some sort of hover-over state
* the reference gets shortened. It always got shortened. Not an issue with this in particular.
* the minimized sidebar is not functional. The copy button doesn't do anything
* looks all funky in safari (not for me)
See merge request !2736
Fix the "x of y" displayed at the top of Issuables' sidebar
1. We now display the index of the current issuable among all its project's
issuables, of the same type and with the same state.
1. Also, refactored a bit the Issuable helpers into a new `IssuablesHelper`
module.
1. Added acceptance specs for the sidebar counter.
Note: I didn't add a CHANGELOG item since it's a bug fix for an unreleased version.
Fixes#13356.
See merge request !2818
Eager-load image blob data in diffs
Since gitlab_git 8.0, blob data are lazy-loaded so we have to call
`blob.load_all_data!(repo)` to eager-load them.
Fixes#13458.
/cc @jacobvosmaer @dblessing @rspeicher
### New image in commit view
#### Before

#### After

### Replaced image in commit view
#### Before

#### After

### Deleted image in commit view
#### Before

#### After

### Image diff in merge request diff view
#### Before

#### After

See merge request !2830