Improve specs a tiny bit.
Whitespace.
Move the indifferentiation helper to Que.indifferentiate so that it's more broadly usable.
When executing SQL, always call #to_a on the result, since there's not much point in passing PG::Result objects around.
Expand comment a bit.
Add Que.worker_states, which queries the database and returns all currently-locked jobs and info on their workers.
Add Que.job_stats, which queries the database and returns statistics on the different job classes.