Sync generatedocbook with operations-guide
Sync generatedocbook with operations-guide

Merge change Ieb32ed8bfb0b6880040e47e3700b812f81598d8a that
was only applied to operations-guide.

The commit has this header:
  commit b47d0fb6335fc91e018a27f4cdae867169e0d459
  Author: KATO Tomoyuki <tomo@dream.daynight.jp>
  Date:   Tue Jul 9 13:45:06 2013 +0900

    Add Docbook XML mode in tools/generatedocbook

Change-Id: I3466e7f762f3257e42bf62bdd292df01749b9164

savinash47/openstack-doc-tools,savinash47/openstack-doc-tools,openstack/openstack-doc-tools,savinash47/openstack-doc-tools,openstack/openstack-doc-tools