Batch interface

One problem with the current erlang module (that I buggered, and @aeden fixed) is that it makes a HTTP request for every stat sent. While it being async is helpful, the overhead is still far too big.

So, I made a module that will batch up stats and send them every `Timeout` seconds. Unfortunately this means that the module only supports using a single `EzKey` which is specified at start-up, but I don't see that as a large problem. 

This module also doesn't have support for the classic API at all (due to it not allowing posting JSON to my knowledge).

Another problem with the code is that it will continue to re-send failed batches forever, with no backoff or count to abandon trying after. This could be a large problem, but I doubt it'd be so hard to solve eventually.

The message API is *not* compatible with the stathat.erl module, but does now have support for timestamps (indeed it adds them if they're left out).

Any questions/comments do send them my way.