Compatible with GitLab 6 and GitLab CI 3 and some benefits

Changes
* Updated all relevant files to support new versions
  - GitLab 6-1-stable
  - GitLab Shell 1.7.1
  - GitLab CI 3-1-stable
  - GitLab CI Runner master
* Strictly seperated GitLab and GitLab CI
  - Now you can install GitLab CI without installing GitLab and GitLab Shell
* Put Git and Ruby handling 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
  - Place a script into profile.d instead
* Updated Tests
* Updated README
* Added GitLab Ci Runner Recipe
* Support development environment
  - Possible alternative to https://github.com/gitlabhq/gitlab-vagrant-vm
* Tested on Ubuntu 13.04 with Chef 11
* Tested on Ubuntu 12.04 with Vagrant 1.3

Backward compatibility
If including the default recipe the behavior is changed as follows
- Git gets installed by git::default
  * For old behavior: Set default[:gitlab][:git][:include_recipe] = "source"
- Remote Backup to AWS S3 is disabled
  * For old behavior: Set default[:gitlab][:backup][:remote][:handler] = ['aws_s3']
- Ruby gets installed through package, only on platforms 'redhat','centos','scientific','amazon' we use ruby_build
  * For old behavior: override_attribute default[:gitlab][:install_ruby] = '1.9.3-p392'

I've created a PR for the original gitlab-cookbook 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, so I decided to put the work in this repository.

Questions and Feedback are welcome!

Thanks for the work & Best regards,
Johannes