[r=blake-rouse][bug=1553617][author=mpontillo] Fix bug #1553617: rack registration fails when bond interfaces are present.
* When parsing '/sbin/ip addr' and gathering driver information, ignore
bonds with no backing interfaces.
* After parsing '/sbin/ip addr', cross-reference data from
/proc/net/bonding/* and update interface MACs with the original
hardware MAC. (After a bond interface is added, the interface MAC is
updated to be the same as the bond MAC, which was throwing off the data
MAAS gathered.)