Update base scenarios for the Mitaka release.
I've updated the two basic scenarios to support Mitaka release.
This PR is about starting the discussion about :
- The mitaka support
- The way we reorganize the git to support the future releases of OpenStack
For the second item I propose to
- create a branch to support the liberty release
- keep master up-to-date with the latest release (here Mitaka)
In the future old release will be supported in dedicated branches and current release will be in master.