Implemented audit.create notification

In this changeset, I implemented the audit.create notification.

Change-Id: Ia092ca3a3dc951e3313a07f15a98aec5818e9ab0
Partially-Implements: blueprint audit-versioned-notifications-api

watcher/objects/audit.py

@@ -236,6 +236,11 @@ class Audit(base.WatcherPersistentObject, base.WatcherObject,
         # notifications containing information about the related relationships
         self._from_db_object(self, db_audit, eager=True)
 
+        def _notify():
+            notifications.audit.send_create(self._context, self)
+
+        _notify()
+
     @base.remotable
     def destroy(self):
         """Delete the Audit from the DB."""

watcher/objects/base.py

@@ -155,7 +155,7 @@ class WatcherPersistentObject(object):
                 if obj[rel_id]
             )
             for obj_field, related_obj_cls, rel_id in loadable_fields:
-                if db_object.get(obj_field) and obj[rel_id]:
+                if getattr(db_object, obj_field, None) and obj[rel_id]:
                     # The object field data was eagerly loaded alongside
                     # the main object data
                     obj[obj_field] = related_obj_cls._from_db_object(