[Reviewer: Andy] Make upstream_hostname match sprout_hostname (fixes #98)

Andy,

Please can you review this fix to make `upstream_hostname` match `sprout_hostname` on all-in-one nodes.  This ensures that sprout recognizes itself in the Route header.

As well as fixing the direct issue, I've also
*   added upstream_hostname to the OVF /etc/clearwater/config, so that at least it behaves the same as AWS
*   fixed up AWS's other parameters to use hostnames rather than IPs where applicable.

I've live-tested for AMI but not (yet) for OVF.

Matt