Compatible with GitLab 6 and GitLab CI 3 and some benefits

This is a Work In Progress PL.

What still needs to be done:
- Update tests to reflect the new changes
- Add GitLab CI Runner recipe
- Update README to explain how to use the recipes (instead of triggers)
- Add some credit for atomic-penguin ;-)

What already happened:
* Updated all relevant files to support new versions
  - GitLab 6.0.1
  - GitLab Shell 1.7.1
  - GitLab CI 3.1.0
* Strictly seperated GitLab and GitLab CI
  Now you can install GitLab CI without installing GitLab and GitLab Shell
* Seperated Git and Ruby into own recipes
  Now you can decide if you want to install Git/Ruby from package or from source
* Changed Webserver to be configurable (like database)
* Removed writing of bashrc and placed a script into profile.d instead
* Removed attribute-triggers (*_enabled)
  This is now handled with recipes instead
* Tested on Ubuntu 13.04 with Chef 11

Thanks for the work so far! I made some of this changes myself the last days (https://github.com/atomic-penguin/cookbook-gitlab/pull/39) - but your repository makes a really good impression, especially because of the tests and stuff, so I decided to put some work in here.

Questions and Feedback are welcome!

Best regards,
Johannes