docs(openstack): fix instructions

The openstack instructions were a mix of new/old commands and
wouldn't work on a lot of openstack installs.

These documentation and changes to the provisioning script should
allow for more variation in openstack installs.

This has been tested as working against both a Havana and Juno release
of Openstack.
docs(openstack): move OpenStack docs to docs site
Merge pull request #2783 from carmstrong/pr-2604

OpenStack: fix instructions and move to docs site
chore(controller): update django-cors-headers to 1.0.0

See https://github.com/ottoyiu/django-cors-headers/releases/tag/1.0.0