Add a new option, -N, which prints out the name of the VLAN number
assoicated with the named VLAN.. Output format: <vlan_name> <stack> <vlan_number> (This is so the user can, if they want, look for more than one VLAN on more than one stack at a time.) This should make some of the control-net firewall code cleaner. For now, though, it's pretty inefficient, becuase it calls listVlans() on the whole stack, which is much more than needed. But, a more efficient implementation will require a change to the switch/stack API.