A sink that serializes statsite data to json, yaml or ruby's marshal.

Just a sink that I though might be useful to someone else. It merges current and previous collections, while aggregating counters, and serializes them to a file. In my use case, the dumped data is consumed by Munin. I find that generating metrics with a statsd client, collecting them with statsite + this sink and charting them with munin works great.

This might be a bit too specific, so I wouldn't mind if you didn't merge it. Just putting it out there.

Example output file:

```json
{
  "temperature": {
    "kv": 34.0,
    "ts": 1360068658,
    "type": "kv"
  },
  "listeners": {
    "sum": 163.0,
    "ts": 1360068658,
    "type": "counter",
    "sumsqrt": 163.0,
    "mean": 1.0,
    "count": 163.0,
    "stddev": 0.0,
    "min": 1.0,
    "max": 1.0
  },
  "login-time": {
    "sum": 24216.0,
    "ts": 1360068658,
    "type": "timer",
    "sumsqrt": 13935574.0,
    "mean": 484.32,
    "count": 50.0,
    "stddev": 212.24172203275342,
    "min": 132.0,
    "max": 885.0,
    "P50": 431.0,
    "P95": 826.0,
    "P99": 885.0
  }
}
```