Unit test user app

* adds unit test for User model and forms
* refactors functions from user_checks.py into User class and drops user_checks.py

api/views/views.py

@@ -18,7 +18,6 @@ from compensation.models import EcoAccount
 from ema.models import Ema
 from intervention.models import Intervention
 from konova.utils.message_templates import DATA_UNSHARED
-from konova.utils.user_checks import is_default_group_only
 from user.models import User, Team
 
 
@@ -321,7 +320,7 @@ class AbstractModelShareAPIView(AbstractAPIView):
         for team_name in new_teams:
             new_teams_objs.append(Team.objects.get(name=team_name))
 
-        if is_default_group_only(self.user):
+        if self.user.is_default_group_only():
             # Default only users are not allowed to remove other users from having access. They can only add new ones!
             new_users_to_be_added = User.objects.filter(
                 username__in=new_users