Comment 7887b3f41a invented a wrong
way which violates the recent PTI. This commit clean them up and
follow the new PTL for documentation build.
The detail is described in the following links:
https://governance.openstack.org/tc/reference/project-testing-interface.html
http://lists.openstack.org/pipermail/openstack-dev/2017-December/125710.html
pbr autodoc is now converted into sphinxcontrib-autodoc.
http://lists.openstack.org/pipermail/openstack-dev/2018-April/129147.html
Change-Id: I158440ef40426593981774307af982028573042b