Add stats publishing support

* Various flags are available to enable or disable certain statistics
* Stats are published to a local statsd instance, where they can be
relayed to a graphite server so a large volume of stats can be collected
* A helper script exists which is run from cron to publish additional
statistics not built into swift statsd reporting like capacity details

Change-Id: I64bd50e270b3f9f41808c4a08f6f811400fb12bd
Merge "Add stats publishing support"