Add a statsd input

[pyr]

It would not take much to have a statsd listener in addition to the carbon one, our storage schema in cassandra makes the listener part stateless, which is a nice addition

[addisonj]

I am interested in having statsd support as well, but am confused as to how you could do it without state?

Would you simplify pre-calculate all the values over the sample, write them to the store, and then just re-write them as needed?

If you wanted to give a bit more direction, I might be interested in trying my hand at a PR on this one.

[pyr]

Hi,

There are several ways to go about it. A first implementation could assume all statsd requests come in to the same cyanite process, I don't think it's necessary to implement it in a stateless way for now.

What this would mean is keeping an atom of counters and rates and flush out values at every interval