Add actual statsd aggregator to tool

[johnseekins]

Primary things:

1. What example statsd implementation could we use? https://github.com/influxdata/telegraf/blob/master/plugins/inputs/statsd/statsd.go is pretty simple...
2. How do we ensure we can use this or forward to another instance (to preserve backwards compatibility)
3. the aggregated data should be persisted to disk so restarts don't lose our stats
4. Since we're persisting, we need a way to delete stats we no longer want to emit
5. We'll want to be able to in some way visualize the usage of our aggregator (likely stats that show how many values we have)