added settings controller
[script/server] don't reassign ARGV
[script/job_scheduler] forgot PID_DIR
[delayed_job] decreased sleep_delay
[tracks] added UUID
[itunes parser] use REXML instead of nokogiri
[models/track] fixed validations
[models/track] try to find track based on attributes
[models/track] added support for filesytem_id
[scanner jobs] added get track helper method
[DirectoryScannerJob] delete nonexistent files