BZ #1158680: Reassign PXE subnet when bond created on primary

https://bugzilla.redhat.com/show_bug.cgi?id=1158680

When the primary interface is involved in a bond, reassign the
Provisioning/PXE subnet to the bond to which the primary interface is
involved.
Merge pull request #372 from bcrochet/bz/1158680

BZ #1158680: Reassign PXE subnet when bond created on primary