Extend live/staging/dev commands to include Chimera.

Let me just say e.g. "staging gen", just like I already could for Impala boxes.

For live Chimera boxes, where there are multiple locations, the live command
takes a third arg, for the location, e.g. `live api1 us`.  If none is given,
defaults to `us` (as that's the location I'm working on usually).  (I may
disable the defaulting later, to avoid potential confusion.)