Enable RHEL3 support on oVirt/RHEV

RHEL3 was precluded before as it lacks virtio drivers, enable it by
using emulated drivers instead.

Bug: 884901
Change-Id: I3a2b9b3086c0a9b6e4bc0da463f8ba188b1d906a
Merge "Enable RHEL3 support on oVirt/RHEV" into develop