Publishing results to job.id Redis channel.

This is helpful when we are en-queuing a job to RQ from any other language and want the sync feature.

Use case:
  Enqueue a job from golang client.
  Python workers pick the job and publishes the result to a Redis channel.
  golang client waits for this result and consumes it as soon as it is received.

This is similar to sync feature in Python RQ client, but uses Redis's PUBSUB feature.