removed extra_sign_in_text examples for gitlab.rb [ci skip]

I removed the extra_sign_in_text option documentation. This is no longer needed because a welcome message aka. extra_sign_in_text can now be set/changed in the admin UI.  

Admin area > Settings

This was mentioned in issue #3006

See merge request !1565

LDAP email address downcasing

Fixes #2960

In the event we cannot match an LDAP user by DN we attempt to find an identity by email address and then update the DN. In this case the identity is matched by email address. 

If the user's email address in LDAP has an upper case character we cannot find a match in the GitLab database. GitLab downcases emails before the user object is saved.

This merge request downcases the email from LDAP before we lookup by email. I also added a test to prevent a regression.

See merge request !1550

Remove slim

Closes #2897 

See merge request !1537

[ci skip]

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

Remove whenever gem

Closes #2879 

See merge request !1538

[ci skip]

Update CHANGELOG for Emoji fix in a3c6ed5c

[ci skip]

See merge request !1556

[ci skip]

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

Normalize space-like characters in keys before output to gitlab-shell

gitlab-shell expects only one tab separator per key, and an SSH key with
a tab character in the comment, for example, would break things.

Closes #2970

See merge request !1552

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! 💥

See merge request !1553

Clarify support request message

Since we have the (GitLab.com) Support Forum, this message may be slightly confusing. Hopefully this wording improves understanding. If anyone has suggestions on making this clearer I'm open.

See merge request !1406

Add task to disable 2FA for all users

Addresses #2971 

See merge request !1532

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

Fixed positioning of hamburger menu on header

Hey guys just noticed the hamburger menu for the top navigation was mis-aligned on 
`gitlab-ce:master` and `gitlab.com`.
I was not able to find an open issue or merge request directly referencing this issue so thought I would add a quick fix.

### Changes

This MR changes the vertical positioning from `top` to vertical margins (Like in bootstrap itself).
 - Also added a minor fix to remove `border-top` from the collapse menu so its the same height as the navigation.
 - finally added an active class to the hamburger toggle so you can see when its open.

This changes an element in `app/views/layouts/header/_default.html.haml` and thus would impact most pages behind login.

## Screenshots

### Before

![before](https://gitlab.com/hanloong/gitlab-ce/uploads/e3d4631dd0420ec0e9048c435a2f734b/before.png)

### After

![after](https://gitlab.com/hanloong/gitlab-ce/uploads/7c93c3ef1b01fbefc39c5a1ed61c2d1b/after.png)

Happy to discuss any changes/suggestions.

Thanks

See merge request !1541

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

 - Changed to margin for vertical allign as used in bootstrap 3 original
 - Also added an `active` state to show when the extra items are enabled

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! 💥

gitlab-shell expects only one tab separator per key, and an SSH key with
a tab character in the comment, for example, would break things.

Closes #2970