Allow for multiple machine-type clusters

[ihodes]

Would be nice if every job didn't have to run on a e.g. 50gb pod when most jobs probably require way less.

e.g. a job that makes an HTTP API call should run on a 1gb node, not a 50gb node

If it were possible to schedule multiple jobs at the same time on the same pod (am I using this word correctly?) then this would be less of a problem, but still not ideal.