#249 Created as modified

* fills modified attribute on new entries with created value automatically
* adds default ordering by last modified on table overviews

api/utils/serializer/v1/compensation.py

@@ -64,6 +64,7 @@ class CompensationAPISerializerV1(AbstractModelAPISerializerV1, AbstractCompensa
         obj = Compensation()
         created = create_action
         obj.created = created
+        obj.modified = created
         obj.geometry = geometry
         return obj