Resque.delayed?

* Resque.delayed? MyJob => Boolean

``` ruby
  # Discover if a job hs been delayed.
  # Examples
  #   Resque.delayed? MyJob
  #   Resque.delayed? MyJob, id: 1
  #   
  # Returns true if the job has been delayed 
  def delayed?(klass, *args)
    !scheduled_at(klass, *args).empty?
  end
```