Parse the worker families and handle SCHEDULING
Parse the worker families and handle SCHEDULING

In the previous commit I forgot to parse the JSON-encoded worker family
list. This happens to work out ok most of the time but can select too
aggressively. We also needed to special-case handling of SCHEDULING as
it is not an actual task class.

Houzz/luigi,Houzz/luigi,Houzz/luigi,Houzz/luigi