Document the feature freeze starting on the 18th

cc @dzaporozhets @rspeicher @DouweM @rymai @axil 

See merge request !3698

Show project members only for members

fixes #5838 

See merge request !3752

Attempt to create pg_trgm extension in migration for test/dev environments

See merge request !3805

Fix cross-project label ref used with invalid project

When cross-project label reference was used with invalid project reference, `nil` was assigned to project variable which later caused an exception.

Closes #15168

See merge request !3811

add tap coverage example to project settings

Previously, there were examples for Simplecov, pytest-cov, and phpunit.
This adds an example for using the tap cli tool
(https://github.com/tapjs/node-tap)

Before:
![Screen_Shot_2016-04-07_at_9.57.32_AM](/uploads/2864d4cd4b5288565057263a435a851f/Screen_Shot_2016-04-07_at_9.57.32_AM.png)

After:

![Screen_Shot_2016-04-07_at_9.57.16_AM](/uploads/62901e01c4ad6db86e4ced3dfebd20b9/Screen_Shot_2016-04-07_at_9.57.16_AM.png)


See merge request !3597

Ci::Commit becomes a Pipeline object

1. Ci::Commit receives context: ref, :tag.
1. One Ci::Commit describes a one Pipeline
1. Pipeline is created from `.gitlab-ci.yml`
1. Pipeline is a ordered group of builds
1. We test MR against Pipeline
1. Pipelines have a separate view (https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/3703)
1. Pipeline can be triggered from UI (https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/3703)
1. Later we change `Trigger -> TriggerRequest -> Build` to `Trigger -> Pipeline` (future)
1. We add a Pipeline Hook that will be triggered on Pipeline status change  (future)
1. We extend notifications to use `Pipeline Hook` to send summary on pipeline changes (future)

After merging that I'll prepare a separate MR that will unify naming, database columns, table names:
```
Ci::Commit -> Pipeline
Ci::Build -> Build
CommitStatus -> Job
GenericCommitStatus -> ExternalJob

ci_commits -> pipelines
ci_builds -> jobs
```

This MR implements first 5 points.

This is made to solve this issue https://gitlab.com/gitlab-org/gitlab-ce/issues/14149.

See merge request !3653

Closes #15168

Closes #15210

Disable spellcheck and autocorrect for username field in admin page

closes #14855

## before
![Screen_Shot_2016-04-19_at_9.25.12_AM](/uploads/19387c4a11a879e9034a2179e932436e/Screen_Shot_2016-04-19_at_9.25.12_AM.png)

## after
![Screen_Shot_2016-04-19_at_9.25.47_AM](/uploads/60f4eba6a97201333dc64e46d625aac2/Screen_Shot_2016-04-19_at_9.25.47_AM.png)

See merge request !3730

Refresh page according remaining todos

Fixes #14678 

See merge request !3428

Fix setting of "action" for Grape transactions

After wondering why we're not getting all the data in Grafana that I
wanted I realized I wasn't setting the "action" field properly here.

See merge request !3842

Wrap all code in diffs

Closes #15382  
Closes #15422  
All diff code wraps to next line instead of scrolling

<img src="/uploads/ec5754919bac0b027fcb122bb88435b3/Screen_Shot_2016-04-20_at_12.22.27_PM.png" width="500px">

See merge request !3838

[ci skip]

Add due date to issues

Closes: #12709

See merge request !3614

Merely setting the "action" tag will only result in the transaction
itself containing a value for this tag. To ensure other metrics also
contain this tag we must set the action using Transaction#action=
instead.

Articles on proper commit messages

2 Articles on commit messages

[ci skip]

See merge request !3831

Add Sentry logging for JavaScript errors

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/12675

See merge request !3795

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Fixed issue with dropdown not being toggleable again