Prepare Installation and Update docs for 8.4 RC1

[ci skip]

See merge request !2401

See merge request !107

[ci skip]

[ci skip]

Revert "Remove the `:coffee` and `:coffeescript` Haml filters"

This reverts commit ae7de2f8.

Several files in EE still use the `:coffeescript` filter and
I don't have time to fix them before the CE-to-EE merge.

See https://gitlab.com/gitlab-org/gitlab-ee/builds/553647

I will reintroduce this change in a future MR.

See merge request !2400

[ci skip]

Also reformats paragraphs for a max width of 80 chars

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Closes #152

This reverts commit ae7de2f8.

Change milestone close notice copy. Closes #6051



See merge request !2372

Improve admin area button style

A lot of the buttons in the top right in the admin area were too big. This makes those the new `btn-nr` size which seems to look nice.

## User buttons

### Current

![Screen_Shot_2016-01-08_at_2.29.30_PM](/uploads/8920d4a67ff4a20617e5b4d319ba154e/Screen_Shot_2016-01-08_at_2.29.30_PM.png)

### New

![Screen_Shot_2016-01-08_at_2.29.21_PM](/uploads/494741f6e92592ff2c60683f399bb1c1/Screen_Shot_2016-01-08_at_2.29.21_PM.png)

## Project edit button

### Current

![Screen_Shot_2016-01-08_at_2.29.59_PM](/uploads/09a2f8fddc45120510dd10758ce33c51/Screen_Shot_2016-01-08_at_2.29.59_PM.png)

### New ![Screen_Shot_2016-01-08_at_2.30.14_PM](/uploads/93a72a7c42b1974643b1e9ffd3ec8511/Screen_Shot_2016-01-08_at_2.30.14_PM.png)

## Label button

### Current

![Screen_Shot_2016-01-08_at_2.38.09_PM](/uploads/9cff790e1a4e2d650487c9765d0235a4/Screen_Shot_2016-01-08_at_2.38.09_PM.png)

### New

![Screen_Shot_2016-01-08_at_2.38.31_PM](/uploads/9462ff2393249eb762dc7cb92605c733/Screen_Shot_2016-01-08_at_2.38.31_PM.png)

cc/ @jschatz1 @creamzy @skyruler 

See merge request !2351

Add CHANGELOG entry for 8.3.4

[ci skip]

See merge request !2393

Never heard of gitlab-omnibus

See merge request !2388

Use gitlab-workhorse 0.5.4

Fixes routing errors for /api/v3/projects/

See merge request !2391

See merge request !2392

added make command to docs

The gitlab-workhose update docs are missing a make command

See merge request !2281

See merge request !2389

Where a vew is called from doesn't matter as much. We already know what
action they belong to and this is more than enough information. By
removing the file/line number from the list of tags we should also be
able to reduce the number of series stored in InfluxDB.

Fixes routing errors for /api/v3/projects/

This gives a very rough estimate of how much memory is allocated during
a transaction. This only works reliably when using a single-threaded
application server and a Ruby implementation with a GIL as otherwise
memory allocated by other threads might skew the statistics. Sadly
there's no way around this as Ruby doesn't provide a reliable way of
gathering accurate object sizes upon allocation on a per-thread basis.

Add user's last used IP addresses to admin page

This would help admins figure out from where spam is originating.

Screenshot:

![image](/uploads/984005a3a35b7004bd0a363081eb53ba/image.png)


See merge request !2381

Improve button styles

I noticed a couple of buttons don't match the newer styles.

## Issue edit note form

### Current (cancel button is big)

![Screen_Shot_2016-01-08_at_2.18.29_PM](/uploads/c7928e6644e886090f55cb61076c9e89/Screen_Shot_2016-01-08_at_2.18.29_PM.png)

### Now

![Screen_Shot_2016-01-08_at_2.18.22_PM](/uploads/d15c3c458a08ce5a59c367c7fb379c31/Screen_Shot_2016-01-08_at_2.18.22_PM.png)

## Merge request code discussion

### Current

![Screen_Shot_2016-01-08_at_2.21.37_PM](/uploads/b970ff3e5d9ef5e62f83bb56d5505f8d/Screen_Shot_2016-01-08_at_2.21.37_PM.png)

### Now (Also changed to `btn-save` class which changes to green. This matches everything else)

![Screen_Shot_2016-01-08_at_2.22.01_PM](/uploads/ed520de72177de92efe21d236bb04d24/Screen_Shot_2016-01-08_at_2.22.01_PM.png)

cc/ @jschatz1 @skyruler @creamzy 

See merge request !2350

See merge request !2385

I forgot to add these in the respective MRs.

[ci skip]

This would help admins figure out from where spam is originating.

Bump fog to 1.36.0

Updates AWS regions and fixes a number of bugs. Tested a GitLab AWS backup without any issues.

Closes #4231

See merge request !2373

adds hover titles to merge request and issue pages

Fixes #5899

See merge request !2375

changes bolded on active for dropdowns, sitewide.

Fixes #6056 <br/>
 **Note:** this change applies to all dropdowns. Currently all dropdowns using bootstrap's dropdown.js apply a bold and larger font for an active state.

See merge request !2377