Added support for 2i pagination.  Changed 2i's and List Keys to use Riak's result streaming by default behind the scenes, but it may not be exposed in the nodiak API that way for a variety of reasons.  For instance if I don't aggregate the results in nodiak from a 2i query then I can't de-dupe it.
Changed the Bucket class to aggregate all 2i keys before fetching them async and sending them up through the nodiak streaming API.