Fixes #2270 - Detect all Openstack IPs and test which allows SSH

This allows a user to not set the floating network if Foreman will be able to reach the VM anyway (either on it's private network, or because a public address will be assigned to it anyway, without Foreman requesting it).

There's a commented out check at the moment relating to #1113 - once that is merged we can say that SSH-provisioning can fail if no IP exists with port reachable, but for UserData-provisioning, it's fine to not have direct access from Foreman.