Basic support for building a gem
* lib/mk/node.rb (hw_id): recognize interface names satrting with 'em'

This makes it possible to use the MK on Fedora 18
* lib/mk/script.rb: require 'json', since we use to_json

Without that, registration fails
* lib/mk/server.rb (send_register): include target host in failed conn error
* bin/mk: support a --daemon flag

This is the hokiest of daemons, just a while loop with a sleep.
Build a LiveCD with the MK agent in it and set to run