neutron: don't set router_delete_namespaces
neutron: don't set router_delete_namespaces

It's no longer available in Neutron (removed in Mitaka). See:
I2a879213c3b095a007a4531f430a33cea9fdf1bd

Change-Id: I044c648eb8c4933667b8ea2c9159a30e5ebb7df3

dprince/tripleo-heat-templates,dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,openstack/tripleo-heat-templates