Using newer statsd version

Using newer versions of statsd, the calculations on timers are already provided. This patch uses those values rather than calculating them manually in this backend.

Also, The counter values also have counter rates provided. This gives you the count/interval time. This patch adds those values to the output.

I'm also working on a completely different way of doing this that involves just flattening the metrics object for output. This would be beneficial because it would automatically pick up any new metrics coming out of statsd. The downside is that it could break your circonus metrics since the names might change between versions. I don't think this is much of a risk if the version of statsd you are using is pinnned and doesn't update on its own. I will submit that in a different pull request though, so you guys can pick which way you prefer.