Refactored global permissions to filter permissions
Created FilterPermission model #77 Done
Created basic tests for Filter Restriction
Changed account_user field name to accountuser
Created FilterRestrictionBackend and applied it in settings
Granted that the permission is assigned or unassigned from user when the filter restriction is created, modified or deleted
Refactored AccountGroup to related with group instead of inheritance. Now the FilterPermission can be assigned to an user or group of permissions. #75 Done
Merge pull request #23 from henriquecf/75-create-filter-permission

75 create filter permission