Removed deadline, version, extra & host_aggregate

As we are about to version the Watcher objects, we need to make sure
that upcoming model/object modifications are additive in order to
avoid having to bump the major version of the API. Therefore,
this changeset removes 4 unused DB fields that were exposed in their
associated Watcher objects (i.e. AuditTemplate and Audit).

Change-Id: Ifb0783f21cd66db16b31e3c8e376fc9d6c07dea3
Partially-Implements: blueprint watcher-versioned-objects

watcher/tests/api/v1/test_audits.py

@@ -87,7 +87,7 @@ class TestListAudit(api_base.FunctionalTest):
         self.assertEqual([], response['audits'])
 
     def _assert_audit_fields(self, audit):
-        audit_fields = ['audit_type', 'deadline', 'state', 'goal_uuid',
+        audit_fields = ['audit_type', 'scope', 'state', 'goal_uuid',
                         'strategy_uuid']
         for field in audit_fields:
             self.assertIn(field, audit)