Implemented the rate limiting from Redis

- Uses Redis cache to check for current count
- If not present then sets the value based on the database state
- Any Redis errors are swallowed. Cache failures should NOT fail  the request.

config.py

@@ -132,7 +132,7 @@ class Config(object):
     STATSD_HOST = "statsd.hostedgraphite.com"
     STATSD_PORT = 8125
 
-    REDIS_ENABLED = False
+    REDIS_ENABLED = True
     REDIS_URL = "redis://localhost:6379/0"
 
     SENDING_NOTIFICATIONS_TIMEOUT_PERIOD = 259200
@@ -166,6 +166,7 @@ class Development(Config):
 
 
 class Test(Config):
+    REDIS_ENABLED = False
     NOTIFY_EMAIL_DOMAIN = 'test.notify.com'
     FROM_NUMBER = 'testing'
     NOTIFY_ENVIRONMENT = 'test'