factor out parts of setupNetworks for better readability

Change-Id: Icb26c288b8f466e5f1009d889dacf3e17d45891c
Signed-off-by: ibarkan <ibarkan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/35691
Reviewed-by: Dan Kenigsberg <danken@redhat.com>