add statsd support

[catdad]

For better reporting and long-running environments.

https://github.com/etsy/statsd

[catdad]

Consider adding a reporter interface instead.

For API access, it's pretty easy... grandma already returns a stream, and it's even easier when using an object stream.

For the CLI, it could be something like --reporter statsd, where it attempts to require a module called grandma-statsd-reporter and use it through the API.