Cluster Rebalancing Functionality

[alexkiousis]

htools.py contains a protype function that invokes hbal

There is no programmatical way to talk to hbal, and there seems to be no way to get a computer-readable output of the commands to execute.

Nevertheless, a function that parses hbal output and understands what jobs to submit could be handy. We can then create a Celery task that submits those jobs and rebalances a cluster.