Persist filters when sorting on user admin page

Closes #2806

See merge request !1543

In SSH key detailed view, align the "Remove" button with the right container

Also fixes a bootlint warning.

Before:

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/d6d8765ed9dceb6a31a6b4475b2166e1/image.png)

After:

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/8252211125ace212335aa6bf2ba78549/image.png)


See merge request !1555

Make diff file view easier to use on mobile screens

Viewing diffs on a mobile screen is a bit of an awkward experience at the moment. Here are a few issues (by no means complete):

## Before

### Tabs are scrunched

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/45924e36cfb107dc56795a7dcdfbc5b5/image.png)

### Filenames take too much room, buttons cluttered

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/a5e5611271fe26dfd3922aa0b8780458/image.png)

## After

This MR makes a few tweaks to make this a bit better. It just addresses a few issues, but there is plenty of room for improvement (e.g. shrink fonts, etc.):

### Eliminate padding to make tabs fit

![image](https://gitlab.com/gitlab-org/gitlab-ce/uploads/fbcf128d1f221b9b9e53df274238dc62/image.png)

### Make filenames, buttons more readable

This screenshot allows the filename to use the whole row, omits the file mode changes, and puts the buttons centered in the view:

![image](https://gitlab.com/gitlab-org/gitlab-ce/uploads/d2e5b9424f058827ba2552056c516e18/image.png)

Towards a better mobile experience: #2787 

See merge request !1449

Restore placeholders in issue filters from "Any" to "Milestone" and "Label"

1f11096c included new filters but made it hard to determine which dropdown did
what. This patch restores the original placeholders.

### Before

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/2326b836e364275341ea0ad8c0a0926b/image.png)

### After

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/b0e519f9cf8d1a3c0f054286e3b809cb/image.png)


See merge request !1554

Make the loading spinner toggle more explicit

Occasionally the loading spinner would stay visible after the tab
finished loading. This change makes the toggle explicit so that it's
always shown on `beforeSend`, and always hidden on `complete`.

Plus a bonus semi-colon eradication! :boom:

See merge request !1553

Show message if user tries to fork and has no available namespaces

This merge request improves the UX when users try to fork a project and have no eligible namespaces. 

### Current behavior

![Screen_Shot_2015-09-25_at_1.39.45_PM](https://gitlab.com/dblessing/gitlab-ce/uploads/45a303703a0197e78f7f9bdbea8718b5/Screen_Shot_2015-09-25_at_1.39.45_PM.png)

### Proposed behavior

![Screen_Shot_2015-09-25_at_1.38.57_PM](https://gitlab.com/dblessing/gitlab-ce/uploads/613c53bcfb52d79fdf8bd1d09410c152/Screen_Shot_2015-09-25_at_1.38.57_PM.png)

### Things to check

I'm not exactly loving the wording I have here. I'm open to improvements.


See merge request !1441

1f11096c included new filters but made it hard to determine which dropdown did
what. This patch restores the original placeholders.