WIP: Upgrade Redis

So, I think this is correct.

However, this is completely untested (besides manually comparing the resulting templates).

I can not simply pull the new redis in parallel with the old one because, well, I don't know what will happen if we spin up 2 redis on the same data bucket.

Given that the new redis changes the service name, we need a reconfigure or a restart of omnibus, so we should probably test out when it's not busy.

This sits on top of !3 (merged).

Cc: @daniels