Ability to move issue to another project

Tasks:

- [x] Create scaffold of service that will move issue to another project.
- [x] Close old issue, add system note about moving issue to a new project.
- [x] Create a new issue, add system note about issue being moved from old project.
- [x] Check if issue can be moved to another project before executing service
- [x] Check permissions when moving an issue (`:admin_issue` ability)
- [x] Display select box for a new project when editing an issue
- [x] Show only projects that issue can be moved into in that select box
- [x] Add project select handler, helper and some permission filters to it
- [x] Preserve as much information as possible, including author
- [x] Prepare mechanisms that unfolds local references in issue description
- [x] Rewrite issue description with references unfolding and add some specs for it
- [x] Rewrite all system notes and comments attached to issue that is being moved
- [x] Update `Label` so that is was able to create cross reference labels (separate MR)
- [x] Add notifications about moving issue to another project
- [x] Display confirmation alert/message when issue move has been requested
- [x] Make it possible to undo selecting project where issue will be moved to
- [x] Add column to issue, that will indicate if it has been moved to another project
- [x] Do not allow to move issue that has been already moved
- [x] Write top-to-bottom feature spec in RSpec instead of Spinach

UI:

![issue_move_ui](/uploads/b3c6b563362c1fded9082cc0f51e5a74/issue_move_ui.png)

![issue_move_tooltip](/uploads/2ab913b06f52df1cafde9abe89bd9cb8/issue_move_tooltip.png)

Closes #3024

See merge request !2831

Use gitlab-workhorse 0.7.1

A small extra defense against interrupted git raw responses. Nice to
have in 8.6 because we introduce /raw/ caching; it would be
unfortunate if incorrect (truncated) responses got cached.

See merge request !3330

Fix diff image view modes (2-up, swipe, onion skin) not working

Example test case: https://gitlab.com/mrtzcspr/test/commit/5d983226b1308d98ef3d8919b978ad49f34496b8

Closes #13856

See merge request !3316

Use the configured Kaminari "per page" default

Configured in [`config/initializers/kaminari.rb`](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/config/initializers/kaminari_config.rb).

See merge request !3320

Backport premailer and diff changes from EE

Backport part of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/151

See merge request !3318

Upgrade Rubocop from 0.35.1 to 0.38.0

See [Rubocop's Releases page](https://github.com/bbatsov/rubocop/releases) for more info on what changed.

Descriptions/StyleGuides removed as discussed in #14233.

Changes:
- Enable DisplayCopNames for lint output.
- Default behavior for `Alias` changed, set to enforce `prefer_alias_method`.
- Enabling Rails cops changed to new syntax.
- Remove StyleGuides and move Descriptions to comments.
- Add missing cops.
- Add TODOs for cops that should be enabled in the future.
- Set TargetRubyVersion to 2.1.

See merge request !3197

Discussed in #14233.

See [their releases](https://github.com/bbatsov/rubocop/releases) for
more info.

Changes:
- Enable DisplayCopNames for lint output.
- Default behavior for `Alias` changed, set to enforce `prefer_alias_method`.
- Enabling Rails cops changed to new syntax.
- Remove StyleGuides and move Descriptions to comments.
- Add missing cops.
- Add TODOs for cops that should be enabled in the future.
- Set TargetRubyVersion to 2.1.

Fix a few remaining uses of `0px`.

See #14299 for more information.

cc: @jschatz1 

See merge request !3310

Make HTTP(s) label consistent on clone bar

Sites that use http:// for the external_url should always display HTTP on
the clone bar. Similarly, sites that use https:// should show HTTPS.

Currently, the inconsistency looks like:

![http-magic](/uploads/945fda580f7ba5aee36cc572b49baf2b/http-magic.gif)

Also restores the tooltips that vanished in 7ba4482f:

![image](/uploads/b5a7b3e68b4992a447fcaa51915e866c/image.png)


See merge request !3319

Fix spacing below edit note form

Also changed to allow the CSS to decide what should be hidden when editing

Thanks @JobV for having eagle eyes 😜 

See merge request !3306

Expand the issuable sidebar when coming back from the Changes tab

Unless the user explicitly requested the collapsed sidebar.

Fixes: #14353

See merge request !3256

Fixed issue with filtered data persisting when dropdown closed

![labels](/uploads/4b9c902add76263d8488cc34ef49f142/labels.gif)

Closes #14401

See merge request !3302

* master:
  Fix bug where wrong commit ID was being used in a merge request diff to show old image
  Remove CHANGELOG item that was added during merge resolution
  Improve the "easy WIP & un-WIP from link" feature
  Fix specs
  \#to_branch_name now uses the iid as postfix
  Add label description in tooltip to labels in issue index and sidebar
  Easily (un)mark merge request as WIP using link
  Use specialized system notes when MR is (un)marked as WIP
  another attempt to fix oauth issue
  attempting to fix omniauth problem

Conflicts:
	app/assets/javascripts/issuable_form.js.coffee

Sites that use http:// for the external_url should always display HTTP on
the clone bar. Similarly, sites that use https:// should show HTTPS.

Fix bug where wrong commit ID was being used in a merge request diff to show old image

Closes #3769

Closes #14327

See merge request !3300

Closes #3769

Closes #14327

Easily (un)mark merge request as WIP using link

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/3768 and https://gitlab.com/gitlab-org/gitlab-ce/issues/3516

## Link to add `WIP` prefix (underline is visible because of hover)
![wipless_title](/uploads/72a6f7119ba9d8043ca8329641e97c3b/wipless_title.png)

## Link to remove `WIP` prefix
![wip_title](/uploads/8620ad65da9ef620b180603520fead55/wip_title.png)

## System note after WIP is added
![wip_sysnote](/uploads/2de073b75e854d2c9e243eb8b5d5c259/wip_sysnote.png)

## Widget with link to remove WIP
![wip_widget](/uploads/cf83ea93743c4c26d9df759c17cb9d7b/wip_widget.png)

## Flash after WIP is removed
![wip_flash](/uploads/27b7240cd5d7ceeb8b7b477abd94d7ff/wip_flash.png)

## System note after WIP is removed
![wipless_sysnote](/uploads/c0d3368abdf21a2f253532a9a9594d90/wipless_sysnote.png)

## Widget when current user cannot remove the WIP prefix
![wip_widget_unauthorized](/uploads/174ccf1674be86dc81c3078fe297acb7/wip_widget_unauthorized.png)

cc @creamzy 

See merge request !3006

# Conflicts:
#	Gemfile.lock

attempting to fix omniauth problem

Attempt to fix https://gitlab.com/gitlab-org/gitlab-ce/issues/3361

See merge request !2876

Add label description in tooltip to labels in issue index and sidebar

The tooltip can get quite big, but it’s so useful to inform people about what these labels mean
new

![Screen_Shot_2016-03-08_at_11.48.28](/uploads/894baaaa1f789c3a2069a924d541e64b/Screen_Shot_2016-03-08_at_11.48.28.png)

![Screen_Shot_2016-03-08_at_11.48.20](/uploads/efe4fa0960054c4071b8f6bf83024403/Screen_Shot_2016-03-08_at_11.48.20.png)

@JobV writes on Slack:
> yeah I think it’s better than not, but I’d have to try it 😃 
> 
> cautious yes, revert if it’s annoying 😉

See merge request !3124

#to_branch_name now uses the iid as postfix

Given the branch name 'mep-mep' with an iid being 1,
the current way, master's way, would yield a branch name of
1-mep-mep. The problem for larger projects however would be that
a developer might forget what iid the issue was.

When this developer would try to tab complete it would:
- Or result in 20+ branches possibly
- Or start with the wrong digit, try again with digit++
  - Would see 20 branches, repeat

Thus the obvious way of solving this is letting the dev tab complete
on the issue title, which is easier to remember.

@DouweM Should this be labelled `pick-in-master`? 

See merge request !3308

Commit 43d8bdb4 introduced additional
checks for permissions to read issue in references extractor.

* master: (121 commits)
  Dedupe labels in labels selector in Dashboard pages
  Refactor colors and lists
  Add a safeguard in MergeRequest#compute_diverged_commits_count
  Fix an issue when the target branch of a MR had been deleted
  Add avatar to issue and MR pages header
  Cleanup somce css colors
  Re-group scss variables
  Refactor `Todo#target`
  Fixes issue with filter label missing on labels & milestones
  Rename `Todo#to_reference` to `Todo#target_reference`
  Fixed failing tests
  Updated controller with before_action Fixed other issues based on feedback
  Fixes issue on dashboard issues
  Full labels data in JSON
  Fixed issue with labels dropdown getting wrong labels
  Update CHANGELOG
  Use `Note#for_project_snippet?` to skip notes on project snippet
  Use `Commit#short_id` instead of `Commit.truncate_sha`
  Reuse `for_commit?` on conditional validations
  Update schema info comment on todo related files
  ...

Conflicts:
	app/models/issue.rb
	db/schema.rb
	spec/models/issue_spec.rb

According to endbosses' suggestions.

Add information about `image` and `services` field at `job` level in the `.gitlab-ci.yml` documentation

Fixes #14366

/cc @tmaczukin @ayufan @axil

See merge request !3277