Add token delete command for identity v2

Identity v2 has undocumented support for token delete and
keystoneclient also has support.

Change-Id: Ib98d17958ceb88f7b63471691dee71fdb884ce2e
Closes-Bug: #1318442
Add a docs job to tox.ini

A noticed that there wasn't a docs option when running tox.
Thought it would be a good idea to add one.

Partial-Bug: #1331304
Change-Id: I5af9ff5d5986ad546146c0fa73eb98256fd00c5f
Update docs template

To make things more consistent across all openstack projects, the
developer docs should be upgraded to the newer template used by
keystone and keystoneclient (and other projects).

I dropped in the necessary static files and themes, and updated
the config file to make the changes at build time.

Change-Id: I5a268cff3cd5af29ad712705d540b9d1d6667d56
Partial-Bug: #1331304
Merge "Add token delete command for identity v2"
Merge "Add a docs job to tox.ini"
Merge "Update docs template"