Tweak new rebalance scheduler

Randomized the order of rebalance tasks in each stealer's list. This
will avoid biasing the rebalance based on the order tasks were
generated.
Addressed review feedback on rebalance scheduler

RebalanceController
- Changed default parallelism to "infinite" since scheduler throttles parallelism
- Added TODOs for cleanup of scheduler
- Added javadoc to document scheduler and its methods
- Catch exceptions, log them, re-throw as VoldemmortRebalancingException

A ton of white space changes due to futzing with eclipse code formatter preferences. Sorry.