Fix a deadlock with debug clients

I've switched to a much more sensible way of cleaning up closed
debug clients.

Fixes #9.
Clean up logging

- No longer print graphite messages when debug = true (the debug
  console is the right way to get this info)
- Don't prefix debug logs with DEBUG (it's unnecessary)
- Debug printing for when debug clients {dis}connect
Add an aggressive write deadline for debug clients

This prevents them from slowing gost down.