Initial support for posting results to StatsD

1. Adding a fully configurable statsd module to allow publishing results to a dedicated server for visualization of trends.
2. Embeding Domnikl/Statsd in the lib directory for the statsd protocol publishing phase.
3. This is a feature that seems to be used/request allot for webpagatest like done in [WptScript](https://github.com/etsy/wpt-script).

Output sample with [Grafana](http://grafana.org/) dashboard:
![image](https://cloud.githubusercontent.com/assets/3163605/5009809/09297b24-6a74-11e4-8e3e-d788637d65f0.png)

Many thanks for making this project !
Presumably the license should also go under lib/statsd-php (or wherever the rest of it ends up).