Updates after review

- Modified the services_dao to return an int instead of a datetime to
make usage easier and removed the BST function on year as it is not
relevant for year
- Improved tests do there is less logic by ordering the result so there
is less reliance on the template id
- Renamed variable in stats_template_usage_by_month_dao.py to make it
consistent with the method

app/config.py

@@ -244,7 +244,7 @@ class Config(object):
         },
         'daily-stats-template_usage_by_month': {
             'task': 'daily-stats-template_usage_by_month',
-            'schedule': crontab(hour=00, minute=50),
+            'schedule': crontab(hour=0, minute=50),
             'options': {'queue': QueueNames.PERIODIC}
         }
     }