blueprint keystone-documentation
Added use case flows in the doc/design folder showing these scenarios:
- User only knows Keystone URL and not their tenant or Nova URL
- User knows their tenant; shortcut of first scenario
- User knows Nova URL only and wants to authenticate
Also added Middleware Architecture explanation to RST docs showing
the many supported deployment scenarios.
Change-Id: I308ac26b2b8748e8a80f4c5952f8311f99d50b40