Bulkloading Historical Data

The changes below support loading full hours of data, in pre-compacted format into the data store.

Basically, this batches an hour of puts into a single put.
Either this should be ``Const.MAX_TIMESPAN * 1000 * 4`` or use the ``ensureCapacity()`` method on every write. The reason being that someone could import 3 million millisecond data points for a single row (hopefully not!) and that would overflow this buffer.