Fix 404 page when viewing TODOs that contain milestones or labels in different projects

A user viewing the TODOs page will see a 404 if there are mentioned milestones or labels in multiple different projects. This is likely a caching bug and only occurs
when Markdown rendering occurs across multiple projects, which is why it's so tricky to reproduce. This is what I think is happening:
    
1. LabelReferenceFilter#references_in encounters label ~X for ProjectA and finds the label in the DB as id = 1.
2. LabelReferenceFilter.references_in yields [1, 'X', nil, ...]
3. Since project_ref is nil, AbstractReferenceFilter#project_from_ref_cache caches nil => ProjectA.
4. LabelReferenceFilter#references_in encounters label ~Y for ProjectB and finds the label in the DB as id = 2.
5. LabelReferenceFilter.references_in yields [2, 'Y', nil, ...]
6. AbstractReferenceFilter#project_from_ref_cache lookups nil and returns ProjectA. It was supposed to be ProjectB.
7. A is the wrong project, so the label lookup fails.
   
This MR expands the `project_ref` to the right value as soon as we have it to avoid this caching bug.
    
Closes #17898


See merge request !4312

Ensure project name is present on page

## What does this MR do?
Fixes a failing spec




See merge request !4307

Fixed JS error when trying to remove discussion form

## What does this MR do?

Fixes a JS error which was caused by an ID of the form not matching what was returned by the JSON. Instead of checking that, it gets the current form from the ajax success event.

This would only happen on outdated discussions because the ID of the discussion form ends with `-false` because it isn't active. However, the note is added to an active discussion so the ID returned actually ends in `-true` & therefore the JS couldn't find the correct form.

## What are the relevant issue numbers?

Closes #17778

See merge request !4303

Fix gitlab importer issue

Fixed credentials not being called correctly - probably some bad refactoring or search & replace... 

Fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/565

See merge request !4301

Fixed issue with button color when no CI enabled

## What does this MR do?

Fixes an issue with the color of the merge button when no CI is setup.

## What are the relevant issue numbers?

Closes #17844

## Screenshots

![Screen_Shot_2016-05-25_at_09.58.44](/uploads/87aac74c5e2f8bfd2831e99c5915856d/Screen_Shot_2016-05-25_at_09.58.44.png)

See merge request !4287

Move tags to column in generic_commit_status

Part of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4249    

cc @ayufan 



See merge request !4277

Improve design of Pipeline view

## What does this MR do?

Improves current design of Pipelines view when there is multiple stages.
This makes the statuses clickable and makes the view more compact.

## Screenshots (if relevant)

![Screen_Shot_2016-05-21_at_01.20.40](/uploads/dd031b7af7005c7a61f3165fefa8b7c9/Screen_Shot_2016-05-21_at_01.20.40.png)

cc @DouweM @markpundsack @rspeicher @marin 

See merge request !4230

Fixed potential issue with 2 ci status polling events happening

Possible cause for double notifications was if the request was slow & then you changed page whilst this request was happening it would finish on another page & then launch another interval - this stops that issue.

Also passed in the CI status as an option value rather than waiting for the first ajax request to finish

See merge request !3869

[ci skip]

Fix concurrent request when updating build log in browser

If you have a slow internet connection the trace will not be updated correctly. We need to check if our request is the latest one.

Fixes: https://gitlab.com/gitlab-org/gitlab-ce/issues/17535

See merge request !4183

Fixed issue with enter key selecting wrong option in dropdown

If you search for a label and press enter the dropdown will select the last element rather than the first. This is because the currentIndex is -1 rather than 0

![labels](/uploads/eb29924109947fd63fea32e21471f05a/labels.gif)

Closes #17630

See merge request !4210

Fixed issue with merge button color

![Screen_Shot_2016-05-19_at_12.51.35](/uploads/a2768908553961e88c5a8f0e1f343078/Screen_Shot_2016-05-19_at_12.51.35.png)

Closes #17644

See merge request !4211

Update branch name from 8-7-stable to 8-8-stable

Fix inconsistency with the command listed above.

[ci skip]

See merge request !4274

Fix typo in link on monitoring help page

Closes #17809

[ci skip]

See merge request !4281

Fix backups if registry is disabled

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/17749

See merge request !4263

Fix builds page

Fixes #17736    
Fixes #17703 

- Move tags into column
- Put column headers back

<img src="/uploads/57609fd2d65c3b80f57b32cbbe316653/Screen_Shot_2016-05-23_at_10.20.37_AM.png" width="800px">    



See merge request !4249

Fix Error 500 in CI charts by gracefully handling commits with no durations

## What does this MR do?

In the CI charts, this MR reports the duration of a commit to 0 if it is `nil`.

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

Should we omit this commit from the chart or set it to some other value?

## Why was this MR needed?

We were getting an Error 500 here: https://gitlab.com/gitlab-org/gitlab-ce/graphs/master/ci

## What are the relevant issue numbers?

#17730 


See merge request !4245

Fix Error 500 when accessing application settings due to nil disabled OAuth sign-in sources

## What does this MR do?

When upgrading to GitLab 8.8, an admin would encounter an Error 500 due to a `nil` `disabled_oauth_sign_in_sources`. This MR ensures that the value will be a blank array if empty.

Closes #17564

See merge request !4242

Initial version of user documentation of container registry

cc @axil


See merge request !4244

Allow anonymous user to access pipelines

## What does this MR do?

It fixes an issue where the Pipelines is shown for the Anonymous users,
but they get 404 when clicked. Their session is then logged out.

Fixes #17717.

See merge request !4233

Added remove due date button

In the sidebar when there is a due date a link to remove due date becomes visible

![remove-due-date](/uploads/126baa61f5ec44ce503ce374d5331ba6/remove-due-date.gif)

Closes #17392

See merge request !4209

Docker container registry configuration docs.

Part of gitlab-org/omnibus-gitlab!764 and gitlab-org/gitlab-ce!4040

See merge request !4141

Allow anonymous user to access pipelines

## What does this MR do?

It fixes an issue where the Pipelines is shown for the Anonymous users,
but they get 404 when clicked. Their session is then logged out.

Fixes #17717.

See merge request !4233

[ci skip]

Fix MySQL compatibility in zero downtime migration helpers

## What does this MR do?

This MR fixes MySQL for zero downtime migration helpers introduced in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/3860

Closes #17711

See merge request !4239

Fix the CI login to Container Registry (the gitlab-ci-token user)

## What does this MR do?

This fixes `docker login` not succeeding when trying to do CI login: `gitlab-ci-token with $CI_BUILD_TOKEN`.

cc @marin

See merge request !4236