Udp server

This pull request is not intended to just be merged without thought, but I thought I might as well start discussion around the UDP server (rather than TCP).  I would anticipate that this would be a huge request for many people, because TCP is not fire and forget and this way my app that sends data to fnord has no requirements on redis, and sending my data causes no real performance hit (with TCP I have to wait for ack, etc).

This is related to the following issue: https://github.com/paulasmuth/fnordmetric/issues/20

## Anticipated points of contention
I would anticipate that you still desire the ability to offer the TCP server for backwards compatibility reasons (though in fairness, I definitely think it is the Wrong Sort of Thing for this kind of app).  My code rips it out entirely, but if you want to provide configuration support for choosing one or the other, just give me some pointers on what you want to see and I'll gladly provide it.

Can we get a discussion started around this?  I'm going to be using my fork starting today, but I would prefer it be merged if it's good with you.  Thanks again for fnord!