Fix cross-references that contain underscores

### What does this MR do?

Cross-references that contain underscores confuse the Markdown renderer and don't work properly. For example:

1. In  `myacct/project_one#456`, add a comment that includes a reference to `myacct/project_two#123`.
2. The comment in `myacct/project_one#456` links correctly.
3. The system note in `myacct/project_two#123` is incorrectly linked as:

`mentioned in issue myacct/projectone#456_`

This MR removes the use of the `_` character in the system notes to prevent Markdown confusion.

See a full discussion in #1160.

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

To preserve backwards compatibility with existing system notes, there is a SQL wildcard match for notes having underscores. This seemed safer than migrating all notes.

### Why was this MR needed?

In an ideal world, the Markdown parser would be able to handle references containing underscores with or without escape sequences. However, there are a number of issues:

1. RedCarpet's parser for emphasis block is pretty dumb: it treats `#` as a word break and thus even the `intra_word_emphasis` flag has no effect.
2. The parser is in C and can't be changed easily.
3. There is no way to insert an escape sequence for emphasis blocks.

The only way around this is to switch to something like CommonMark, which does support escape sequences.

### What are the relevant issue numbers / [Feature requests](http://feedback.gitlab.com/)?

Issue #1160

### Screenshots

Before:

![Screen_Shot_2015-03-19_at_1.39.29_AM](https://gitlab.com/gitlab-org/gitlab-ce/uploads/a1db4b96c0df2f10d9855ed5abe976ca/Screen_Shot_2015-03-19_at_1.39.29_AM.png)

After:

![Screen_Shot_2015-03-19_at_1.39.35_AM](https://gitlab.com/gitlab-org/gitlab-ce/uploads/189a062c2d19645eec1782ac1f0d4f2f/Screen_Shot_2015-03-19_at_1.39.35_AM.png)

See merge request !385

Update poltergeist to support phantomjs 2.0

In response to [my issue](https://gitlab.com/gitlab-org/gitlab-development-kit/issues/36) on the GDK.
PhantomJS 1.8 was not in the repo's anymore. Only poltergeist needed it, but they support PhantomJS 2.0 since 1.6.0. (next release since 1.5.1) [Their CHANGELOG](https://github.com/teampoltergeist/poltergeist/blob/master/CHANGELOG.md).

Tested locally with Ruby 2.1.5. As this took ages, I haven't tested further.

See merge request !403

Fixed rake task gitlab:cleanup:block_removed_ldap_users

Maybe not the most elegant solution, but it works for us.

This closes issue gitlab-org/gitlab-ce#955.

See merge request !338

Add canceled CI status

Fixes https://github.com/gitlabhq/gitlab-ci/issues/564

https://dev.gitlab.org/gitlab/gitlab-ci/issues/169

![Screen_Shot_2015-03-19_at_17.10.08](https://dev.gitlab.org/gitlab/gitlabhq/uploads/87f47d9fd1b1a60e0c5402eedd1a1566/Screen_Shot_2015-03-19_at_17.10.08.png)

See merge request !1729

fix(style): align navbar-toggle

Changes:
- change `.navbar-toggle` from `margin: 0 -15px 0 0;` to `margin: 0;`

## Before:
- 320x480 ![Screen_Shot_2015-03-19_at_03.43.53](https://gitlab.com/kingcody/gitlab-ce/uploads/376727af07cf62eec5609c01bbbdaacf/Screen_Shot_2015-03-19_at_03.43.53.png)

- 360x640 ![Screen_Shot_2015-03-19_at_03.44.04](https://gitlab.com/kingcody/gitlab-ce/uploads/d5318de4f45687154d90c54f0bece2aa/Screen_Shot_2015-03-19_at_03.44.04.png)

## After:
- 320x480 ![Screen_Shot_2015-03-19_at_03.45.21](https://gitlab.com/kingcody/gitlab-ce/uploads/20f526c9ef19c2c30add001b15c06358/Screen_Shot_2015-03-19_at_03.45.21.png)

- 360x640
![Screen_Shot_2015-03-19_at_03.45.27](https://gitlab.com/kingcody/gitlab-ce/uploads/e60e9dde1f86d89adf36480e7fcc611d/Screen_Shot_2015-03-19_at_03.45.27.png)

See merge request !402

Only trigger search if search string is present

This is a follow up for !296 to prevent the search function from being executed while the query is nil.

Problem was this:
When the search is called, the search controller gets 2 requests.
```
{"action"=>"show", "controller"=>"search"}
```
and
```
{"utf8"=>"✓",
 "search"=>"proj",
 "project_id"=>"",
 "group_id"=>"",
 "snippets"=>"",
 "scope"=>"",
 "button"=>"",
 "action"=>"show",
 "controller"=>"search"}
```

Obviously it doesn't make sense to execute the search for the first request, since that one doesn't have a scope or a search string.

Please review this carefully since this modifies the search and may break things i can't think of.

@dzaporozhets While this fixes the root cause for the failing test, I think we should keep your fix in as a failsafe. What do you think of this?

See merge request !302

Backup repo with tar instead of git bundle

Fixes gitlab/gitlab-ee#246

See merge request !1723

Fewer Git constants, more Git helpers.

See merge request !1727

Remove emphasis from system notes to avoid Markdown conflicts in names.

Fix link to 'URL auto-linking' section in markdown help

Update rugments, fixes #8976

Fixed spelling mistake in install docs

Fixed spelling mistake of this.

[ci skip]

See merge request !404

Changes:
- change `.navbar-toggle` from `margin: 0 -15px 0 0;` to `margin: 0;`

Remove success signin message by devise

I find it really annoying every time I login into GitLab it shows me
that I successfully signed in. But this makes no sense to me. I already
see dashboard and dont see login screen. Its obvious I signed in
successfully. Instead it just show annyoing message every time taking
part of space on my screen.

See merge request !401

Show test settings as disabled when service cannot be tested.

See merge request !1725

You get redirected after signuout to gitlab.com and see this message on login page which makes no sense.

I find it really annoying every time I login into GitLab it shows me
that I successfully signed in. But this makes no sense to me. I already
see dashboard and dont see login screen. Its obvious I signed in
successfully. Instead it just show annyoing message every time taking
part of space on my screen.

Improve UI

* Improve group rename warning
* Refactor select css. Make selects same width

See merge request !400

Improve diffs UI

* replace big button with simple toggle for diff comments
* replace diff stats button with link

See merge request !399