Use sphinx-build and cleanup unused config.
Switch to openstackdocstheme 1.20.0 and remove obsolete settings from
Update some RST files, they had wrong indentation.
According to Openstack summit session ,
stestr is maintained project to which all Openstack projects should migrate.
Let's switch to stestr as other projects have already moved to it.
Create a tox environment for running the unit tests against the lower
bounds of the dependencies.
Create a lower-constraints.txt to be used to enforce the lower bounds
in those tests.
Add openstack-tox-lower-constraints job to the zuul configuration.
Add missing dev packages for libxml and libxslt to the bindep config
for more details.
Signed-off-by: Doug Hellmann <email@example.com>