This attempts to manage the SSH host keys of all the hosts in the
inventory. The idea here is each host in the inventory will add a
ansible_ssh_host_key_ecdsa_public variable, then when we first run our
bastion playbook we'll properly populate the local known_hosts file each
time.
Change-Id: I26e328192a7127086e514dc62a27cb946a77440b
Depends-On: https://review.openstack.org/643408
Signed-off-by: Paul Belanger <pabelanger@redhat.com>