Look for lower-case hostname when adding to ssh_known_hosts
Look for lower-case hostname when adding to ssh_known_hosts

We need to normalize hostnames to lower-case in order to avoid
case discrepancies.

Change-Id: Iaf73f9ae346425881e70500cf3ee28599fc4171a
Partial-Bug: 1809273

openstack/tripleo-common,openstack/tripleo-common