add columns: queue, priority, attempts, run_at, failed_at, created_at
(de|in)flate timestamp columns as Time::Pieces
enable default values: attempts, run_at, created_at
decrement attempts on run
track some state after running method

If the method succeeds delete the job.  If it fails and there are no
attempts left then set failed_at.
add logger class
bunch of change towards the worker (daemon)
add 'attempts > 0' to query
make command return true when they succeed
need to call update to save changes