Jobtastic - User-Responsive Celery Tasks

There is a typo in the sample code. 'herf_avoidance_timeout = 60'.

It would be neat if we can use the Jobtastic task as a decorator, similar to the celery.task decorator. That way I won't have a bunch of JobtasticTask subclasses, that only differ in the way calculate_result is implemented.

If needed I can set the variables needed by passing kwargs to the decorators instead. It will definitely be easier on the eyes.