Probably I think this should maybe go in the supervisor?  I think the intention of the previous refactor was so all the nova-specific stuff would be in supervisor, and the supervisor could be replaced with a heat worker instead.

The controller (which is poorly named) I guess right now is supposed to be calculating the new capacity, and calling 'converge', which in turn figures out which orchestration to call (heat, vs original otter).

At least that's my understanding - does that sound like what we had discussed previously?  Also, cc @radix