Add ability to see and sort on vote count from Issues and MR lists

Fixes #3763

* Sort options

![Sort Options](/uploads/df6543d574d4df8bf7e4496a876e2930/sort.png)

* Most popular

![Most popular](/uploads/bb92cc2fbef7b6b806dcdf8c52778fdd/most-popular.png)

* Least popular

![Least popular](/uploads/7988ed451922c81dc228419b5edbd7cd/least-popular.png)

See merge request !2781

Refactor 'git archive' hand-off to gitlab-workhorse

We have a nicer way now to hand off HTTP responses to gitlab-workhorse.

Companion MR: https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/36

See merge request !2675

Correct icon for milestones.



See merge request !2856

Sort line notes used in parallel diff by created_at


Fixes #13464.

See merge request !2858

Redirect /import to project page if no importing at all and repo exists


Fixes gitlab-org/gitlab-ce#13367.

See merge request !2857

Fixes #13464.

Handle nil commits in Gitlab::PushDataBuilder.build

Closes #13469

See merge request !2825

Expire caches after forking/importing a repository

cc @dblessing @DouweM 

Related issue: gitlab-org/gitlab-ce#13505

See merge request !2838

Fixes for showing images

- Render scrubbed SVG's inline, not via /raw/
- Use /raw/ requests on image diffs

Both of these are needed because of no longer eager loading blobs.

This a follow-up to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2830

Also see https://gitlab.com/gitlab-org/gitlab-ce/issues/13350

See merge request !2837

Fixes #13367.

Fix a bug preventing from doing subsequent edits in any Issuable sidebar

Fixes #13517. Fixes #12572.

### Issue

![impossible-subsequent-issue-edits-in-sidebar](/uploads/bd45c0effb46848641932d9cd38d3fe2/impossible-subsequent-issue-edits-in-sidebar.gif)

---

### Merge request

![impossible-subsequent-mr-edits-in-sidebar](/uploads/b4e1e3e93df4ac0a3d962df8b6139de9/impossible-subsequent-mr-edits-in-sidebar.gif)

/cc @jschatz1 @sytses 

See merge request !2848

Fix 500 error when comparing by tags

_Originally opened at !2787 by @klowner._

- - -

Fixes #13171.
Fixes #13370.

See merge request !2849

Fix double scrollbar issues

Sidebar double scrollbar issue fix.

![Screen_Shot_2016-02-16_at_9.22.49_PM](/uploads/cb950eda08ed5d3b4a6c6979c977e029/Screen_Shot_2016-02-16_at_9.22.49_PM.png)

See merge request !2851

Prevents floated button group on issues view

Issue #13359 

![screenshot](/uploads/962ac4f3f1f3d6ef87f7152c09090801/screenshot.jpg)

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.

Fixes gitlab-org/gitlab-ce#13505

Updated the allocations Gem to 1.0.4

Sometimes the output of Allocations.to_hash may contain garbage. See
https://gitlab.com/gitlab-org/allocations/commit/15d3a39f51392013dcf5f88dd21fab31201350ce
for more information.

See merge request !2816

[Award Emoji]: sporadic spec fix



See merge request !2833

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

Fix Redis installation guide



See merge request !2839

[ci skip]

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