Remove usage of docbook-properties.sh

The openstack manuals do not use docbook properties anymore, we can
remove setting the properites and also the script docbook-properties.sh.

Current openstack-doc-tools together with the configuration of trunk and
stable/havana and stable/icehouse branches work fine without this.

Change-Id: I97be952aedc06b7c0b6ac1b7e341234c258bdfa3
Merge "Remove usage of docbook-properties.sh"