Don't depend on storage module

There is no real need for hooking module to depend on the storage
module, except for the execCmd which is being delegated to
utils.execCmd, so importing the execCmd directly from utils instead.

Change-Id: Ib36940cda2a07e2898e26e6e7de4d4f3b1292e8f
Signed-off-by: Mike Kolesnik <mkolesni@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/16003
Reviewed-by: Giuseppe Vallarelli <gvallare@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>