Adding basic abilities to code
Display and Structual sets: Treeview changed to tree action to enable easier restriction through CanCan
hyhull abilities:

This commit adds some customised abilities for hyhull.  They include:-
 - Create permisssions override that only specified user groups can create resources (ContentCreators, ContentAccessTeam and Admins)
 - Destroy permissions override that restricts destroys unless resource is in the Proto, QA, or Deleted queue
 - Set Tree view only viewable ContentAccessTeam and Admin
 - Role management is Admin only

Extra users added spec user factory for wider reaching user spec testing.  Abilities spec added to test added Abilities logic.
Integrated Abilities authorise logic into the two controllers ContentMetadataController and FilesController.  This contains:-
 - ContentMetadataController Authorises based upon the permissions defined for ActiveRecord::Base
 - FilesController Authorises based upon permissions for :update against the ActiveRecord::Base