• Removed created, delayed, error, finished, priority, restarted, restarts, started and state methods from
  Minion::Job.
  
• Removed started method from Minion::Worker.
  
• Added support for pluggable backends.
  
• Added modules Minion::Backend and Minion::Backend::Mango.
  
• Added backend attribute to Minion.
  
• Added reset method to Minion.
  
• Added info methods to Minion::Job and Minion::Worker.
  
• Added -L and -S options to job command.