Open Stack

This has two major implications:

1) Master is no longer feature frozen
2) Any future Ussuri bug fixes will need to be backported

Because of 2 and in spite of 1, please try to avoid merging any highly 
invasive changes to master between now and the Ussuri coordinated 
release. If we end up needing a last-minute bug fix we don't want to 
have to disentangle it from a huge refactoring effort (or whatever) in 
order to backport.

Thanks.

-Ben