Changing vdsm-tool and vdsmd pre-tasks outputs to be more meaningful to user

Previously to this change the output was misleading. Users
could not understand how to handle configuration issues properly.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1029812
Change-Id: If29f41081a70c0734cd78dab36f86c794a44b2d3
Signed-off-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/23253
Reviewed-by: Vered Volansky <vvolansk@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>