initial and optional statsd support

this push lacks test, but to be honest I would love to get your inital input on statsd support and how you would approach testing it in your module.

(its been a while since I have committed some java code... so just let me know what you would like to see)
The constant strings are the same, they should be defined correspondingly.
Also, based on my previous comment, when you have a separate StatsdClient, you could keep these static variables in that class, so it's not mixed with kafka properties.