Using old form of zombiereaper

In ovirt-3.3 we don't include the change [1] that modifies zombieReaper
to zombiereaper.

The import in utils.py cause an import error without having [1].

[1] http://gerrit.ovirt.org/#/c/19253/

Change-Id: I7483e09df69d07b8396e075726dd14efb42a5551
Signed-off-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/23215
Reviewed-by: Dan Kenigsberg <danken@redhat.com>