Assign only one IP per node in admin network

Extra IPs are not necessary to ensure reliable
PXE installation. We simply need to add each
MAC to the Cobbler profile to ensure that the
correct profile is chosen.

Change-Id: I0deea1d88f8e99f7743fd3b2df01ebaa8c0d914e
Closes-Bug: #1269726
Merge "Assign only one IP per node in admin network"