Change notificationworker to use a data interface

endpoints/test/test_notificationevent.py

@@ -12,9 +12,9 @@ def test_all_notifications(app):
       'namespace_user': AttrDict(dict(username='foo')),
       'name': 'bar',
     }),
-    'event_config_json': json.dumps({
+    'event_config_dict': {
       'level': 'low',
-    }),
+    },
   })
 
   for subc in NotificationEvent.__subclasses__():