Porting user groups from Exercises WIP
Some more group logic; Added migrations
Initial work on Group and GroupUser API
Factories and updated specs for groups and group users
Added migration to change application owners to groups
Fixed groups migration; migrated schema; simplified app access policy after migration
Moved set_password code and specs into identity code and specs; Added some comments
Group model specs WIP
Model specs
Added supergroup-related models
Removed old group code with access levels
Removed supergroups; Added group sharings
Added sharing spec; Fixed some access policies
Added group sharings controller and representers; enforce that a group is shared with a user or another group
Finished(?) user groups; Added groups index spec
Refactored user groups again
Fixed specs; Added group show specs
Representers now return staff groups; Added create specs
Added group update and destroy specs
Added group user specs