Remove unregister Group
Add group to fieldsets
Add PermissionsMixin to User model
Replace list of fields with __all__
Add group moderator
Add directions for initial data
Add moderator docs
Replace __all__ with need fields
Add moderator user to dummy data
Add users created in dummy data
Fix list formatting
Fix link to usage/groups.rst
Add Moderator group

Add fixture for group "Moderator" with permissions. Add dummy user under the moderator group.