Conflicts:
	config/routes.rb

Minor doc updates

## What does this MR do?

Adds to and clarifies some documentation. Specifically, when using `gdb` to debug you need to detach and exit when done. Next, this clarifies the type of file locking that we require.

Thanks to @northrup for the details about mandatory vs. advisory file locking.

Note: These were two really small changes so I combined in to one merge request. However, I left the commits separate for clarity.

See merge request !4421

Load d3 only when necessary

Now d3 is only loaded on the users' show page and the graphs pages, where it's necessary.

Redo of !3993.

This decreases page size from 4.6MB to 4.3MB for a given Activity page (before compression), or a savings of 300KB. This is essentially a proof of concept for removing larger dependencies such as the Ace Editor, Chart.js, and Raphael, which will likely provide another 1MB of savings on most pages (again, before compression).

See merge request !4394

Remove Coveralls and Semaphore badges. [ci skip]

Remove Coveralls and Semaphore badges from the README. They're outdated,
unused, and not GitLab CI :)

[ci skip]

See merge request !4334

Adds a `title` attribute to the branch dropdown for when the name has been cut off.

Fixes #18056 

See merge request !4395

Upgrade devise, devise-two-factor, and attr_encrypted

Devise 4 includes support for Rails 5, working towards #14286. devise-async doesn't support Devise 4.0 and in 4.1 the bug that was blocking using Devise's built-in ActiveJob integration was fixed. So devise-async is removed. devise-two-factor 3.0.0 is required for Devise 4 support.

attr_encrypted and encryptor are optional but recommended upgrades for devise-two-factor 3.0.0. The mode and algorithm will need to be changed in order to update to attr_encrypted 4.x in the future.

See merge request !4216

Use downcased path to container repository as this is expected path by Docker

## What does this MR do?

Docker Engine requires path to be lowercase. This makes all container registry paths to be show and used downcased instead of mixed case.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/17959


See merge request !4420

Implement new row hover style

## What does this MR do?
Implement new row hover style

## What are the relevant issue numbers?
Closes #17187 

## Screenshots (if relevant)
![Screen_Shot_2016-06-01_at_1.40.04_PM](/uploads/62db01f405db50531fb648e46dc9598a/Screen_Shot_2016-06-01_at_1.40.04_PM.png)   

cc @dzaporozhets 

See merge request !4422

MR widget mobile styling

## What does this MR do?

Corrects MR widget styling for mobile viewing.

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

I have tested all MR states.

## Why was this MR needed?

UX.

## What are the relevant issue numbers?

Closes #17676.

## Screenshots (if relevant)

![Screen_Shot_2016-05-31_at_20.04.02](/uploads/b1bc67b1015b2e771ae1b1364b225618/Screen_Shot_2016-05-31_at_20.04.02.png)![Screen_Shot_2016-05-31_at_20.03.50](/uploads/86a552c0d27d6f53cdf1b94631b26449/Screen_Shot_2016-05-31_at_20.03.50.png)![Screen_Shot_2016-05-31_at_20.03.34](/uploads/a5b9e7b634e974095922df9194d493b5/Screen_Shot_2016-05-31_at_20.03.34.png)![Screen_Shot_2016-05-31_at_20.01.35](/uploads/2fc5d49e3c1f2ff2cb324e9527179066/Screen_Shot_2016-05-31_at_20.01.35.png)![Screen_Shot_2016-05-31_at_20.00.25](/uploads/23af913891ff941dc5231872b3c6f177/Screen_Shot_2016-05-31_at_20.00.25.png)![Screen_Shot_2016-05-31_at_19.59.53](/uploads/8abb72609409ba7ca02ad6b35787c15c/Screen_Shot_2016-05-31_at_19.59.53.png)![Screen_Shot_2016-05-31_at_19.58.31](/uploads/fabf1c6c135f5e736614e568fc4cfb53/Screen_Shot_2016-05-31_at_19.58.31.png)![Screen_Shot_2016-05-31_at_19.58.51](/uploads/967a578a34cb3a9dd3723c2f22ce89c4/Screen_Shot_2016-05-31_at_19.58.51.png)![Screen_Shot_2016-05-31_at_23.33.19](/uploads/841af7a90bb3fc3c74a2e51b64fc444f/Screen_Shot_2016-05-31_at_23.33.19.png)![Screen_Shot_2016-05-31_at_23.33.23](/uploads/183fb8407c271d9aa3fefea5d8201238/Screen_Shot_2016-05-31_at_23.33.23.png)

See merge request !4386

Fix note validation spec failure

Fix failing build due to project of note not matching issue project.

See merge request !4415

Add Edge to supported browsers list.

Add Microsoft's Edge browser to the list of supported browsers. We support the latest stable version.

See merge request !4416

Don't advertise the use of "ci skip" in the CONTRIBUTING guide

[ci skip]

See merge request !4406

Enable Style/Semicolon rubocop style cop

Don't use semicolons to terminate expressions.

See #17478.

See merge request !4351

Enable Style/For rubocop cop

> Do not use `for`, unless you know exactly why. Most of the time iterators should be used instead. `for` is implemented in terms of `each` (so you're adding a level of indirection), but with a twist - `for` doesn't introduce a new scope (unlike `each`) and variables defined in its block will be visible outside it.

See #17478

See merge request !4397

Merge Builds and Pipelines tab into one

Based on https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4053#note_12064642. Main idea is to keep all CI-related pages under one tab. So we can keep top navigation clean. 

First I tried `CI/CD` naming but it looked weird so I just used Pipelines as tab name. I did not change project settings naming. 

cc @ayufan @markpundsack @jschatz1 

See merge request !4340

Separate reference gathering from rendering

This is a required step to allow batch processing when gathering references. This in turn would allow grabbing (for example) all mentioned users of an issue/merge request using a single query.

cc @rspeicher @DouweM 

See merge request !3969