Update openstack-doc-tools to at least 0.17

openstack-doc-tools 0.17 provides the new openstack-dn2osdbk script
needed to build the HOT guide.

Changes since version 0.16.1:

* Added support for *-manage CLI doc generation.
* ``openstack-dn2osdbk``: Converts Docutils Native XML to docbook.
* ``openstack-doc-test``: Handle the upcoming HOT guide.
* ``autohelp.py``: Provide our own sanitizer.
* ``autohelp.py``: Use the oslo sample_default if available.
* ``openstack-doc-test``: Correctly handle SIGINT.
* Various smaller fixes and improvements.

Change-Id: If3c42a50c413eed7efa1f79bf05adfe4eede9a8d
Merge "Update openstack-doc-tools to at least 0.17"