Add gerrit url to reviewday .ssh/known_hosts file

Change-Id: I01a753ecdbd0fcb22cd26ac173f1a37eff35def1
Reviewed-on: https://review.openstack.org/25567
Reviewed-by: Dan Prince <dprince@redhat.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Khai Do <zaro0508@gmail.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins