Add support for Gitlab Container Registry
- Based on the options available in https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template
- Added serverspec test and fixed another serverspec test.
- Removed Gitlab CI Backup. The normal backup takes care of this and also backs up the Gitlab Container Registry, except if you upload it to the cloud
- Removed Gitlab CI separate url and unit test as they are obsolete.
- Updated kitchen.yml with newer boxes.
- Add source_url and issues_url to please foodcritic.
All tests have succeeded on local vagrant with Chef 12.14.60.