Change to new Notes styleguide



See merge request !4625

[ci skip]

Fix migration helper race conditions

## What does this MR do?

This MR fixes two problems with the migration helpers:

1. An error in `change_column_null` would not drop the previously created column
2. `update_column_in_batches` would rely on the number of rows in a table to determine how many to update. This meant that newly inserted rows (after the `COUNT`) would not be taken into account.

This MR also removes an outdated comment for `update_column_in_batches`.

## Are there points in the code the reviewer needs to double check?

No.

## Why was this MR needed?

See above.

## What are the relevant issue numbers?

Fixes #18483

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] ~~API support added~~
- [ ] Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4618

Only show branches for revert / cherry-pick

## What does this MR do?

Stop showing tags in the revert and cherry-pick select options. You can't change a tag anyway.

## Are there points in the code the reviewer needs to double check?

Uncertain.

## Why was this MR needed?

Showing tags doesn't make any sense and will just throw an exception if the user tries to cherry-pick or revert onto a tag.

## What are the relevant issue numbers?

Fixes #18377.

## Screenshots (if relevant)

On the GitLab CE repo:

![image](/uploads/9c5a6f09300a7c46d0a794bef2956992/image.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4596

Change logs.md location in README

## What does this MR do?

Forgotten link from https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4622

See merge request !4623

Move logs/logs.md to administration/logs.md

## What does this MR do?

Move `logs.md` documentation under `administration/` where it fits better.

## Why was this MR needed?

For a better doc structure.

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/3349

See merge request !4622

[ci skip]

Remove notification level from user model

part of #3359 

See merge request !4494

[ci skip]

Tags are immutable, so we can't add a commit to either revert or
cherry-pick another commit to them.

Instead of updating a fixed number of rows (based on the amount of rows
available at the start of the update) the method
"update_column_in_batches" will now continue updating rows until it runs
out of rows to process.

For a table with a high rate of inserts this may result in the migration
taking quite some time. However, the alternative is not all rows being
updated or the "change_column_null" method raising an error due to there
being NULL values.

This ensures that whenever changing the NULL constraint of a column
fails we still drop the column.

Merge branch '18446-when-this-merge-request-is-accepted-this-issue-will-be-closed-automatically-rendered-twice' into 'master'

Resolve ""When this merge request is accepted, this issue will be closed automatically" rendered twice"

## What does this MR do?

1. Only show the above text when there is an MR that will close the issue, and even then, only show it once.
2. Apply 98f147e84d2bd8f2278452ac0852118452c76d4a to a bunch of other places that need it.

## Are there points in the code the reviewer needs to double check?

¯\_(ツ)_/¯

## Why was this MR needed?

Some pages were broken.

## What are the relevant issue numbers?

Fixes #18446.

## Screenshots (if relevant)

Before:
![image](/uploads/23cfaf95b7c798f22963ff67f78a803b/image.png)

After:
![image](/uploads/ca9c538069ba52e53858c69387738521/image.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4594

Improve SVG sanitizer to handle namespaced attributes

* Small refactor in the SVG sanitizer
* Enable already whitelisted namespaced attributes to be allowed
* Disable `xlink:href`to reference any external resource

Fixes #18100 

See merge request !4427

Fix Error 500 when using closes_issues API with an external issue tracker

Closes #18484

See merge request !4608

Closes #18484

Improvements to offscreen navigation

Improvements on top of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4579 based on mockups from https://gitlab.com/gitlab-org/gitlab-ce/issues/18417#note_12389766

See merge request !4607

Resolve "Hide Left sidebar paradigm"

## What does this MR do?
Hides the nav bar by default & centers the tanuki logo in the top nav

## Why was this MR needed?
UX

## What are the relevant issue numbers?
Closes #18417 

## Screenshots (if relevant)
![Screen_Shot_2016-06-10_at_12.49.10_PM](/uploads/c281e4c9de1c1bc9af59ebfa8d2bd18b/Screen_Shot_2016-06-10_at_12.49.10_PM.png)
![Screen_Shot_2016-06-10_at_12.49.27_PM](/uploads/635e0a88230105faa5527f6632899ddb/Screen_Shot_2016-06-10_at_12.49.27_PM.png)
<img src="/uploads/3001a9c723037012f1b86cfacfb1225e/Screen_Shot_2016-06-10_at_12.51.41_PM.png" width="500px">

See merge request !4579

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

Fixed search form padding

## What does this MR do?

Corrects the padding of the search form.

## Are there points in the code the reviewer needs to double check?

Ney.

## Why was this MR needed?

UX

## What are the relevant issue numbers?

Closes #18463.

## Screenshots (if relevant)

![Screen_Shot_2016-06-10_at_14.07.32](/uploads/e4d127c66cf7fa3286279367d6e4ea7c/Screen_Shot_2016-06-10_at_14.07.32.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4591

Only create the backup directory if it is local

Closes #12710

See merge request !4551

Closes #12710

Add Project.where_paths_in

In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4410 I'm working on reducing the SQL queries needed to render Markdown. One reason for the large amount of queries is executing a large number of queries needed to find projects and related data. Basically `Project.find_with_namespace` is called in a loop and then any relations have to be retrieved separately.

By using `Project.where_paths_in` we can work around this by doing something like:

```ruby
project_paths = [...] # populated by some method
projects = Project.where_paths_in(project_paths).includes(:namespace, ...)
```

Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/18042

See merge request !4535

Changelog fix for search dropdown arrow keys fix

[ci skip]

See merge request !4580

Remove unused MergeRequest#gitlab_merge_status method

Closes #18462.

See merge request !4593

Revert side nav to full width; remove border under nav; remove tooltips on nav links; stop page content shifting with side nav; put project nav in container

Move Labels and Milestones as sub tab to Issues/MR

## What does this MR do?

UI/UX change. Moves project labels and milestone tabs under Issues and Merge request tabs. 

## Why was this MR needed?

To solve problem of having to many tabs in top navigation. Since Labels and Milestones depends on Issue/MR feature it belongs to it and can be removed from top nav.

## What are the relevant issue numbers?

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/18368

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md) - not needed
- [x] API support added - not needed
- [x] Tests
  - [x] Added for this feature/bug - changed existing tests to match new behaviour
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)

cc @jschatz1 @annabeldunstone @skyruler

See merge request !4592