circle: update permissions after migration

circle/circle/__init__.py

+# register a signal do update permissions every migration.
+# This is based on app django_extensions update_permissions command
+
+from south.signals import post_migrate
+
+
+def update_permissions_after_migration(app, **kwargs):
+    """
+    Update app permission just after every migration.
+    This is based on app django_extensions update_permissions
+    management command.
+    """
+
+    from django.conf import settings
+    from django.db.models import get_app, get_models
+    from django.contrib.auth.management import create_permissions
+
+    create_permissions(get_app(app), get_models(), 2 if settings.DEBUG else 0)
+
+post_migrate.connect(update_permissions_after_migration)