Provide a celery task init() function

[Muharem Hrnjadovic]

The celery task init() function will be called by every celery task. If it returns False the task will terminate immediately.
The init() function should
    - check whether the job in question is still alive and return False if this is not the case
    - initialise logging using a logger adapter object, http://docs.python.org/library/logging.html#loggeradapter-objects and make sure that way that the job_id appears in the routing key