Open Stack

We now have a working multi-cell CI job for nova proposed [1]. I've 
tried to fully document it both in the job definition and the commit 
message. I'd like this to be voting and gating as soon as possible given 
we've supported multi-cells since Pike so this has been a long-needed 
test environment for nova. However, if we want to be conservative we 
could make this non-voting in the check queue for awhile and then during 
or after the PTG make it voting and gating if people prefer.

Thoughts?

[1] https://review.opendev.org/#/c/655222/

-- 

Thanks,

Matt