Use FQDN instead of IP address to point to keystone host

When using SSL, the common name field in the certificates is checked,
and using IP addresses won't work with that.

Internally to the OpenStack setup, it is always fine to use the FQDN
from the node, so we use this.
Merge pull request #88 from vuntz/use-public-name

Use FQDN instead of IP address to point to keystone host