Rely on new augeas lens for modules.conf and conf.modules

Rely on new augeas lens for modules.conf and conf.modules

Latest augeas includes a lens for /etc/modules.conf. If this new lens is
present, the code to force the Modprobe lens to try to match /etc/modules.conf
as well results in /etc/modules.conf not being parsed at all. This results in
modprobe_aliases in virt-inspector output being empty.

This change is equivalent to change cfd28d1140393667913689b7b9bcf21c8bfe592c
from virt-v2v.

An effect of this change is that the Modules_conf augeas lens is now required
for correct operation on guests which use /etc/modules.conf.

Fixes RHBZ#596776
(cherry picked from commit 245ed4b8eb076a8c4cc5787f49d21c4f68630f9f)