Fix for deleting audit template

We need to update sqlalchemy/api and sqlalchemy/models (and appropriate tests)
to support deleting audit templates and recreating them with the same names.

Change-Id: Icf54cf1ed989a3f2ad689e25be4474b16a3a3eb2
Related-Bug: #1510179

watcher/tests/db/sqlalchemy/test_types.py

@@ -35,6 +35,7 @@ class SqlAlchemyCustomTypesTestCase(base.DbTestCase):
                                 .filter_by(uuid=audit_template1_id).one()
         self.assertEqual({}, audit_template1.extra)
 
+    def test_JSONEncodedDict_extra_value(self):
         # Create audit_template with extra
         audit_template2_id = w_utils.generate_uuid()
         self.dbapi.create_audit_template({'uuid': audit_template2_id,