Add Todos documentation

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/13884

See merge request !3064

[ci skip]

Don't show "Welcome to GitLab" when the search didn't return any projects

Fixes #13785. /cc @pixdrift

### Before

![Screen_Shot_2016-03-02_at_10.55.02](/uploads/b6b6ead2143d01e374ad296e72182d79/Screen_Shot_2016-03-02_at_10.55.02.png)

### After

![Screen_Shot_2016-03-02_at_12.12.33](/uploads/6e16c44e69039c534ea0fc3373c6060b/Screen_Shot_2016-03-02_at_12.12.33.png)

See merge request !3059

Added username to issue & merge request header

Closes #13771 

## Issue header

![Screen_Shot_2016-03-01_at_16.59.32](/uploads/a112dfb91eb9b6f911c716265b35043c/Screen_Shot_2016-03-01_at_16.59.32.png)

## Merge request header

![Screen_Shot_2016-03-01_at_16.59.26](/uploads/67bf9e65ac5cae4667db6c5148cb57a0/Screen_Shot_2016-03-01_at_16.59.26.png)

See merge request !3048

Fix permissions for deprecated CI build status badge

This fixes permissions for deprecated status badge, being unavailable even if project is public.

Closes #13324

See merge request !3030

Show days remaining instead of elapsed time for Milestone.

Closes #13623

See merge request !2978

Check for conflicts before creating new revert branch

Fixes #13716 

See merge request !2953

Add FilterArray class to Banzai



See merge request !3053

Don't load all of GitLab in mail_room

Fixes #12731

cc @jacobvosmaer 

See merge request !3005

Fix wrong anchor in PROCESS.md



See merge request !3060

Fix import from gitlab.com fails

_Originally opened at !2896 by @kazsw._

- - -

Fixes #12652

CGI.escape encodes '/' by default.
Second argument can be removed.

See merge request !2988

[ci skip]

Fixes #12652

Fix help keyboard shortcut for relative URL setups

Fixes gitlab-org/gitlab-ce#12751

See merge request !3016

Bump sprockets to `~> 3.3.5`

Closes #6069

See merge request !3055

Change doc styleguide to use blockquotes for notes



See merge request !3009

Updated SAML and Omniauth docs

Updated SAML and Omniauth docs with information on the new behavior recently introduced in !2882

/cc @ernstvn @DouweM 

See merge request !2950

Closes #6069

Logged out search

Fixes #13676  

See merge request !3045

This changes only deprecated CI badge that we keep for backwards
compatibility. See !3030#note_4041498.

Add a paragraph on "Implementing design & UI elements" in CONTRIBUTING.md

Closes gitlab-com/www-gitlab-com#544

See merge request !2983

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

Also, link to this new paragraph in PROCESS.md and improved a bit this
document.

[ci skip]

Closes #13771

Add customer label explanation and change label references to markdown

Add customer label plus change valid labels to markdown format so they render.

The unchanged labels do not have actual/valid labels behind them. We should consider removing them since they're obviously not used.

cc/ @sytses @dzaporozhets @DouweM What do you think about removing the unused labels?

Label names are now rendered

![Screen_Shot_2016-02-25_at_10.59.03_AM](/uploads/4869416c120422b605df8982a46f6d61/Screen_Shot_2016-02-25_at_10.59.03_AM.png)

See merge request !2972

Return empty array when commit has no statuses in API

This makes API endpoint for Commit Statuses return empty array instead
of 404 when commit exists, but has no statuses.

Closes #3080

See merge request !3010

Fix relative URL

See https://github.com/gitlabhq/gitlabhq/issues/10053

 1. Same configuration way for relative URL like with Omnibus
 2. Loading the relative configuration from Rakefile as Rails do not load initializers for `asset:precompile`

First point has another positive side effect: no collisions (due to git controlled `application.rb`) any more during the upgrades of source based installations and relative url configuration

 - [x] tests on the source based installation
 - [x] tests on the centos&ubuntu omnibus packages

Fixes: gitlab-org/gitlab-ce#13730, gitlab-org/gitlab-ce#13727, gitlab-org/omnibus-gitlab#1143 and https://github.com/gitlabhq/gitlabhq/issues/10053

See merge request !2979

Add bottom margin for flash container on login page
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

cc @jschatz1 @skyruler 

Fixes #13935 

See merge request !3040

Fix issue with overlap of sidebar links.

Thanks @iamphill for the help with this one. 

![Screen_Shot_2016-03-01_at_10.19.52_AM](/uploads/f203fde79ae397ad18f23c4108f1c306/Screen_Shot_2016-03-01_at_10.19.52_AM.png)

cc @iamphill @alfredo1 @dzaporozhets @rymai 

See merge request !3043

Replace Gollum `[[_TOC_]]` tag with result of TableOfContentsFilter

Closes #2494

See merge request !2952

Only validate avatar cropping values when avatar is present AND changed

Closes #13905

See merge request !3018