Add audit.planner events

In this changeset, I implemented the following notifications:

- audit.planner.start
- audit.planner.end
- audit.planner.error

Partially Implements: blueprint audit-versioned-notifications-api

Change-Id: I29d371f8cb3fd7948c87bec97186e24a88e8fdb6

watcher/notifications/base.py

@@ -58,7 +58,8 @@ class EventType(NotificationObject):
 
     # Version 1.0: Initial version
     # Version 1.1: Added STRATEGY action in NotificationAction enum
-    VERSION = '1.1'
+    # Version 1.2: Added PLANNER action in NotificationAction enum
+    VERSION = '1.2'
 
     fields = {
         'object': wfields.StringField(),