Have conduit mapping resolution freak out in a more informative manner.

This lets the recipe detect ahead of time when a network conduit
mapping cannot possibly work on a system.
Simplify compatible bond finding by using Nic::Bond.find
Merge pull request #178 from VictorLowther/pull-req-release-pebbles-master-4e6cc193a8cbbe598d32acfed9e47d422573a504

Make the network recipe die informativly if conduit mapping is insane. [2/2]