Add the SADD to register a queue after using enqueue

[xescugc]

For coherence with the Ruby implementation (and also for the ResqueWeb), when a job is enqueued, the queue must be added to the "resque:queues" this way the ResqueWeb can print it and the jobs that it has.

I don't know how to test this "feature" because the only way would be to query Redis for a smembers resque:queues and see if the queue is there (I've tested that it works on my PC). If this is ok for you I can add a test doing what I've described, but there is no test querying Redis so I prefer to ask first If you would do it this way 😄

[xescugc]

Ping @benmanns

[xescugc]

Totally agree sorry 😄 done 👍

[benmanns]

Thanks!