Support for multiple queues

[lecardozo]

Currently, rworker consumer only listens for one specific queue, which is defined on the object creation via the name argument:

consumer <- rworker(name='celery', workers=2, queue=redis_url, backend=redis_url)

Although this is good for most cases, there are several others in which a consumer should listen for different queues. That said, being able to map tasks to specific queues should be considered for the next versions. The name argument could be used as the default queue when the queue parameter is not defined on tasks.

consumer <- rworker(workers=2, queue=redis_url, backend=redis_url)

my_task <- function() {
    Sys.sleep(5)
}

consumer$task(my_task, name='my_task', queue='my_queue')