The templates at extraconfig/pre_network/host_config_and_reboot.yaml
(replaced with extraconfig/pre_network/boot-params-service.yaml) and
extraconfig/tasks/ssh/host_public_key.yaml (replaced with the
tripleo-ssh-known-hosts role) are deprecated as they do not
work with config-download. They will be removed in the Stein release.
Change-Id: Ib66873ea4b0d86f12024ec16d788247c071cf3b5