Started adding base PermissionsRepository for sub classes to use for assigning permissions, created a BulkImport extension methods for PetaPoco with tests since we'll be needing that for assigning permissions in a nice way. Wrote unit tests for all sql gen for permissions and assigning permissions. This all starts fixing #U4-2161 but there's still a bit more work to do.
Fixes: #U4-2475
Fixes: #U4-2476
Updates ContentRepository to bulk insert all parent permissions at once (overload to the AssignEntityPermissions method)
Fixes: #U4-2161 - permissions inheritance. Fixes up how user permissions cache is invalidated and looked up (it is now lazy and not forced). User permissions are also cached as a low priority for now and only for 20 mins based on #U4-2474.
Merge branch '6.1.3' of https://github.com/umbraco/Umbraco-CMS into 6.1.3