vm: Pause vm in case volume allocation is greater than lv size

Qemu bug is causing qcow to allocate extents beyond the volume's
physical size. In this case we want to avoid extending the volume in
infinite loop and pause the vm, to avoid data corruption.

Change-Id: Id95aa1ed7508218d8ae6a878606cd2d251ac2b05
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=998443
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>
Signed-off-by: Sergey Gotliv <sgotliv@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/19719
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>