Add resque worker to process the captions of a recording

record-and-playback/core/scripts/bigbluebutton.yml

record-and-playback/core/scripts/workers/rap-base-worker.rb

...-and-playback/core/scripts/workers/rap-captions-worker.rb

...d-and-playback/core/scripts/workers/rap-process-worker.rb

...d-and-playback/core/scripts/workers/rap-publish-worker.rb

...rd-and-playback/core/scripts/workers/rap-sanity-worker.rb

...d-and-playback/core/systemd/bbb-rap-resque-worker.service