Expose a batch rate limit request

There are situations where users would like to be able to send a batch request to minimize network roundtrips. The two types of requests that come to mind:

1) Sending rate limit requests for more than 1 domain/key/value tuples.
2) Sending rate limit requests for the same domain/key/value treated as if they were separate requests. There is no work around for this with the current API because summing requests could potentially put you over limit for the entire batch.