Leverage ruby more in new network link test recipes.

From @mihalis68's commit to do network checks, leverage ruby a bit more to make it cleaner and reuse code.

This does work in VirtualBox for me, so let's add it to the default roles.  There is a bug where the ping to a node fails on the first run through of a machine - I'm still debugging that and may hold off merging until I can resolve.  I suspect something is funny with ARP or NAT translations at the VirtualBox layer.