Layer2test

This should be a more complete fix for bnc#855696. I also tried to make the layer2 keyword handling a little more sensible. I couldn't figure out why the previous code was adding a 1 and then subtracting it in various places, so I took that out.

My testing for the two changes seemed to indicate things still work as desired, and the new behavior for prompting for DHCP is only done for Layer 2 devices.