Updated zeroconf.py so as to use standard Avahi calls.

This fixes some multithreading bugs and makes for more elegant code.
Unfortunately, it means ERS no longer works on Mac. Tough.
Minor bugfixes for zeroconf.py
Removed direct usage of zeroconf in ers.py
Updated daemon to use new zeroconf.
Connect to DB in daemon
Added "state" design document
Daemon can now initialize the CouchDB database