New module: 'statsd'

- Remove 'pystatsd' module. It's only applied on hafnium at the moment,
  so I'll clean up behind it myself.
- Add 'statsd' module, which configures Etsy's StatsD.
- Declare histogram for browser latency stats.

Tested.

Change-Id: If65995400913da14dce8ee36c6081efd64a9c1a6