Update Docker Hub and Engine links

1. Update all links to Docker Hub.
2. Update or rename Docker with Docker Engine.

See merge request !4083

We're hiring.

Help with recruiting, saw it in other readme's too.

See merge request !4080

Update SVG sanitizer to conform to SVG 1.1

Original SVG sanitizer would strip out necessary elements and attributes.

Use a custom Loofah scrubber since sanitize 2.x transformers are inadequate to handle case-sensitive SVG attributes since they parse documents as HTML instead of XML, which causes all SVG attribute names (e.g. `viewBox`) to be downcased.

* SVG element list: https://www.w3.org/TR/SVG/eltindex.html
* SVG attribute list: https://www.w3.org/TR/SVG/attindex.html

Closes #14555

See merge request !3401

Reduce delay in destroying a project from 1-minute to immediately

This 1-minute delay was causing confusion among customers. Was there a reason this needed to be 1 minute?


See merge request !3997

Run ProjectDestroyWorker after pending_delete attribute has been committed to DB

Use a custom Loofah scrubber since sanitize 2.x transformers are inadequate
to handle case-sensitive SVG attributes. sanitize parses documents as HTML
instead of XML, which causes all SVG attribute names (e.g. viewBox) to be downcased.

* SVG element list: https://www.w3.org/TR/SVG/eltindex.html
* SVG attribute list: https://www.w3.org/TR/SVG/attindex.html

Closes #14555

Make group settings button white instead of gray for better visibility

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

cc @annabeldunstone @skyruler 

See merge request !4078

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Add nice new Todo bell

![H5bp___Html5_Boilerplate___GitLab](/uploads/e8725396a5d77a8db09742f977595605/H5bp___Html5_Boilerplate___GitLab.png)

![H5bp___Html5_Boilerplate___GitLab](/uploads/011a21ee1653502c4f78543e28d97b67/H5bp___Html5_Boilerplate___GitLab.png)

![H5bp___Html5_Boilerplate___GitLab](/uploads/0858cb9621463ef6a32237fcb0b4f63d/H5bp___Html5_Boilerplate___GitLab.png)

Fixes: #15671 

See merge request !4077

Move group settings navigation to own partial

A bit of refactoring for !3980

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !4076

Align code within links in comments

Closes #17343

<img src="/uploads/78e03c1dc0e99c7bdb686d9d120a4525/Screen_Shot_2016-05-06_at_9.28.26_AM.png" width="800px">

See merge request !4073

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Annotate models

See merge request !4071

Update db/schema.rb after running db:migrate:reset

See merge request !4074

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Redesign navigation for group pages

Part of #14838. This MR targets on desktop version. Mobile version improvements will be in separate merge request 

See merge request !3980

Auto-set title for branches created from issues

This sets the title for a new MR to 'Resolves "$issue-title"' when:
- The source branch for the MR begins with a value iid.
- The MR has more than one commit in its diff (if there's one commit, keep using the commit's first line).
- The iid does not point to a confidential issue.

Single commit:

![A single commit uses the commit title](/uploads/cd34f59cd67f095c3034fae07950f8b5/image.png)

Multiple commits:

![Multiple commits use the issue title](/uploads/a322c406ddd56913c5aebd88d16e5a5e/image.png)

Confidential issue:

![A confidential issue uses the branch name](/uploads/7ae9b79de5f6101ced46802f3c3a6e71/image.png)

cc @DouweM @zj 

Closes #14564

See merge request !3966

Use outer join for issues ordering by milestones due.

This MR contains an implementation for Solution 1 suggested in #14183 

Ordering by Milestone due sooner/later ("milestone sort") filters issues without a milestone, which can let users feel like disappearing issues without a milestone.

See merge request !3872

If a branch starts with an issue's IID, followed by a hyphen, the
description will be updated to say that is closes the issue. This also
updates the title of the merge request to 'Resolves "$issue-title"', as
long as:
- There is more than one commit in the merge request (if there is only
  one commit, the commit's title will be used as before)
- The issue's IID is valid for the project

Update annotations on models



See merge request !3962

Assign labels milestone when moving issue

Closes #14532.

See merge request !3934

Add note to requirements doc on swap recommendation, and ensuring enough available memory.

Called out as a result of 2GB RAM DO droplets not being enough to run backups on without adding a swap file. See: gitlab-org/omnibus-gitlab#1267

cc\ @stanhu @axil 

See merge request !4060

clarify changelog entry on GitHub Enterprise import support

/cc @stanhu 

See merge request !4066

[ci skip]

Rake drop tables with cascade

See merge request !4020

Fix importer bug when throwing exceptions

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/15681

See merge request !3941

Add a note to testing docs about the `:each` argument to RSpec hooks

[ci skip]

See merge request !4061

[ci skip]