Adds in call to new rate limit method in the redis client

- both V1 and V2 APIs
- Rate limiting wrapped into a new method - check_rate_limiting
	- delegates to the previous daily limit and the new though put limit
- Rate limiting done on key type. Each key has it's own limit (number of requests) and interval (time period of requests)
- Configured in the config. Not done on a per-env basis though could be in the future.

app/v2/errors.py

@@ -16,6 +16,19 @@ class TooManyRequestsError(InvalidRequest):
         self.message = self.message_template.format(sending_limit)
 
 
+class RateLimitError(InvalidRequest):
+    status_code = 429
+    message_template = 'Exceeded rate limit for key type {} of {} requests per {} seconds'
+
+    def __init__(self, sending_limit, interval, key_type):
+        # normal keys are spoken of as "live" in the documentation
+        # so using this in the error messaging
+        if key_type == 'normal':
+            key_type = 'live'
+
+        self.message = self.message_template.format(key_type.upper(), sending_limit, interval)
+
+
 class BadRequestError(InvalidRequest):
     status_code = 400
     message = "An error occurred"