Switch from threading to multiprocessing.

At high load levels bucky becomes CPU-bound on socket management and eventually
drops incoming UDP packets. This change moves all UDP servers to separate
processes as well as providing a base process-based client implementation and
a reimplemented CarbonClient on top of it.

On CPU-limited workloads this change improves performance by ~40%.
Fix the tests for multiprocessing.
Bump to version 0.2.0.
Merge pull request #11 from cloudant/multiprocessing

Run each server/client in its own process.
Prevent orphaned child processes on SIGTERM.
Add an option for sending metrics to Graphite via pickle.
Allow bucky.names.statname monkey-patch in config.
Statsd supports floats in gauges but bucky does not (and it should)
Merge pull request #15 from aerofs/master

Statsd supports floats for gauge values but bucky does not accept them.