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.

app/clients/redis/__init__.py

@@ -0,0 +1,5 @@
+from datetime import datetime
+
+
+def cache_key(service_id):
+    return "{}-{}-{}".format(str(service_id), datetime.utcnow().strftime("%Y-%m-%d"), "count")