WIP adding simple benchmarking of jdbc-mget.

This is to help get started benchmarking different database configurations
and queries. It should also be helpful in preventing performance regressions.

As a first step, we can get data from different buckets and then randomize
the lookup of that data in fixed sized chunks. This should allow us to exercise
different parts of the indexes or partitions.

/cc @loganlinn
Commenting.
Whitespace.
Adding methods for summary statistics.

I added the mean, variance, and 95th % to the benchmark results in addition
to the elapsed time. The summary statistics are more interesting than just the
raw elapsed time.
Recording the stop time before doing the accounting.
Merge pull request #20 from drsnyder/benchmark

Benchmarking jdbc-mget