Replacing the manual parsing of the /etc/group file with the equivalent call from the Etc class in the Ruby standard library. This has the benefit of supporting additional platforms (e.g. OS X).
Merge pull request #2890 from cameronyule/support_osx_groups

OS X support for gitlab:check rake tasks
remove commented code
Add state machine gem
Add base of Event base
Add base of Notifications
Subscription base
Add notofication state to notifications
Replace Event class with OldEvent class
replace events with old_events
Add new relations with new events system
fix errors
fix Notification model
db schema after migration
Enumerize gem added
Classes renamed
Actionable added
Actionable added
Event factory added
Notification service added