Adding Sipity::Models::Group
Adding Sipity::Models::GroupMembership
Adding enumeration to GroupMembership
Teasing apart membership roles and meanings
Removing a duplicate spec from refactoring

This spec exists in the more appropriate HeaderQueries module
Factoring in the Membership polymorphic relation
Teasing apart a descriptive method
Adding default group membership
Rename method

Caught a problem on the permissions model
Dropping primary keys for unneeded tables
Adding Group permissioning scope
Adding a TODO item

[skip ci]