Tsuru-circus

This release improves the Stats plugin. Now Stats plugin supports `StatsD` and `Logstash` backends. `StatsD` is the default backend.

The backend is configurable via `TSURU_METRICS_BACKEND` environ.

This release removed all logic from `ProcfileWatcher` plugin.

This release improves the ProcfileWatcher plugin. Now the plugin gets the environs from enviroment variable instead reads the apprc file.

This release improves the Statsd plugin. Now plugins send data about network sent/received, disk usage and connections established.

This release improves the Statsd plugin. Now the plugin sends the sum of the memory stats between the main and children process.

This release improves the Statsd plugin. Now the plugin sends the sum of the stats between the main and children process.