Fix truncate_first_line if message is nil

Fixes https://gitlab.com/gitlab-org/gitlab-ci/issues/255

/cc @jacobvosmaer 

See merge request !217

Use avatars from GitLab

Rewrite Gravatar URLs if needed in order to have images in different size

/cc @dzaporozhets @vsizov 

See merge request !220

Rewrite Gravatar URLs if needed in order to have images in different size

Make YAML validation stricter

/cc @vsizov 

See merge request !218

Randomize test database

/cc @vsizov 

See merge request !219

Added Application Settings

This moves some of the settings from application.yml to Admin page.

![Screen_Shot_2015-07-30_at_12.22.27](https://gitlab.com/gitlab-org/gitlab-ci/uploads/d37aa0003d9afaeb85aa350bb02e6f07/Screen_Shot_2015-07-30_at_12.22.27.png)

/cc @sytses @vsizov 

See merge request !215

Do not use image's file name as alternative text

`image_tag` by default uses the image's file name for the img tag's alt
attribute. This is not preferable in many cases. E.g. it clutters the UI
with a long hash string if a gravatar could not be loaded.

To fix this, the `alt` option is set for `image_tag` calls.

![gitlab-ci-img-alt](https://gitlab.com/dgerhardt/gitlab-ci/uploads/2699d149983912e458e2375fe9732b0d/gitlab-ci-img-alt.png)

See merge request !214

Truncate commit messages after subject line in table

Commit messages are now additionally truncated after the first line.
Before, a commit message's body was attached behind the subject which
made messages hardly readable in some cases.

![gitlab-ci-truncate-commitmsg](https://gitlab.com/dgerhardt/gitlab-ci/uploads/a0c601eb1abbce7a7b9e4e0e3f16f303/gitlab-ci-truncate-commitmsg.png)

See merge request !213

Fix inline edit runner-description

Fixes: #217
Replaced .show and .hide with .removeClass('hide') and .addClass('hide') (Like done for #192 in MR 177)

See merge request !206

`image_tag` by default uses the image's file name for the img tag's alt
attribute. This is not preferable in many cases. E.g. it clutters the UI
with a long hash string if a gravatar could not be loaded.

To fix this, the `alt` option is set for `image_tag` calls.

Commit messages are now additionally truncated after the first line.
Before, a commit message's body was attached behind the subject which
made messages hardly readable in some cases.

Adjust CI config to support Docker executors

A shell script (based on the one for GitLab CE) has been added to
support Docker executors. Tags have been added to make sure builds are
only executed on appropriate runners.

This makes it possible to test forks of the GitLab CI repository on
public runners. Previously, builds failed with the following error:

```
$ bundle --without postgres
/builds/eldamir/gitlab-ci.sh: line 29: bundle: command not found

ERROR: Build failed with: exit code 127
```

See merge request !212

A shell script (based on the one for GitLab CE) has been added to
support Docker executors. Tags have been added to make sure builds are
only executed on appropriate runners.

Detail that people can use script to do `rake rspec` but also to call a `tests.sh`



See merge request !209

* commit '19c8544b':
  update changelog

Fixes a bunch of spelling/grammar mistakes.

There were many spelling mistakes, which ultimately distracted
from the content it was describing. This commit fixes all that
I could find, and rewords some sentences to improve clarity

See merge request !211

There were many spelling mistakes, which ultimately distracted
from the content it was describing. This commit fixes all that
I could find, and rewords some sentences to improve clarity

Update changelog



See merge request !167

Fix invalid link to doc.gitlab.com

/cc @vsizov 

See merge request !207

* commit 'a7d59ed9':
  Fix rendering issues
  Rework CI documentation by adding informations about YAML, the use of Docker images and building them

Fix permission escalation

This fixes permission escalation as described here: https://gitlab.com/gitlab-org/gitlab-ci/issues/225

As this is security fix this commit should be cherry-picked to 7.13: https://dev.gitlab.org/gitlab/gitlab-ci/commit/02982e545744925a6ce8238ed354abdd8e6c835f


See merge request !165