RaP: Clean up resque worker code, add worker for keep_events feature

I've moved the workers code into the `lib` subdirectory with other library-ish
code; this puts it into the ruby load path used by most scripts so referencing
files is easier.

I've applied various style cleanups based on the rubocop config present.

The `events` processing step has been integrated as a new worker `EventsWorker`,
there is no longer a separate `events/events.rb` script. I've reworked the
`rap-starter.rb` script to check for the done files in both the events and
recorded status directories.