Update default config.xml for 2.2. Disable dnsmasq, enable Unbound. R…

…emove

outdated comments that used to sort of document the config file, but had
been neglected for quite some time and aren't all that useful anyway.
Change default NICs from vr to em, given vr is on the way out and em is
the most common NIC in use today. partially re: Ticket #3396