Change postgresql dir to have version and cluster

Using straight /srv/postgres is not so kind on the various postgresql
tools which expect version and cluster name. Plus if /srv/postgres is a
mount point, like in our case, postgres complains about lost+found
existence

Change-Id: Iebce74d7101299e7dea25c2cb798d674e2343108
Merge "Change postgresql dir to have version and cluster" into production