More hostile-network-friendly.

* Lookup the DNS name after 60 seconds (mostly informed by AWS's guidance here).
* Look up all addresses associated with a name, and round-robin through them (again, thanks to AWS and how ELBs work).
* Use SocketChannel, check that we wrote the whole buffer.
* If we fail to send a message, *try again* one time (otherwise, if your messages were widely spaced enough, wouldn't you *never* send a message?)