dnsmasq::client as a loopback resolver

Allow dnsmasq to be run in a "client" configuration, as is the default of
Ubuntu's NetworkManager on desktops nowadays. This is beneficial because:

1. It can provide some safety from upstream failures. dnsmasq will cache
  records for a period of time. It also won't hang in quite the
  unpredictable way that glibc does.
2. It will reduce the chatter of repeated queries for the same resource.
  Such as an application looking up the database hostname on every web
  request.