Remove remaining direct references to the User model. Closes GitLab issue #225.

mayan/apps/folders/tests/test_api.py

@@ -1,6 +1,6 @@
 from __future__ import unicode_literals
 
-from django.contrib.auth.models import User
+from django.contrib.auth import get_user_model
 from django.core.files import File
 from django.core.urlresolvers import reverse
 from django.test import override_settings
@@ -24,7 +24,7 @@ class FolderAPITestCase(APITestCase):
     """
 
     def setUp(self):
-        self.admin_user = User.objects.create_superuser(
+        self.admin_user = get_user_model().objects.create_superuser(
             username=TEST_ADMIN_USERNAME, email=TEST_ADMIN_EMAIL,
             password=TEST_ADMIN_PASSWORD
         )