Code review comment for lp:~drawks/graphite/graphite-msgpack

1. Please move the import of Unpacker from msgpack from module-level to inside connectionMade().
2. (as said on IRC), note that setting the port to 0 effectively disables it, so the 3 new extra settings are not needed. If you do think it's better/more explicit to keep them, then might make sense to remove the 'if port:' from service.py and require setting the ENABLE_* settings instead.