Remove tools/generatedocbook

We use the file from openstack-doc-tools, no need for local versions.

Change-Id: Id9c2760ec557071e17441d18c26acafd12d18576
Update pom.xml to clouddocs-maven-plugin version 2.0.0

Change-Id: I6f0957b4f10c3d01dba1a30691053b489be6b202
author: diane fleming
Merge "Remove tools/generatedocbook"