Enqueue to in

Hi! First of all - thank you for this great piece of software, I like the idea, it's really awesome :]

Recently I migrated project from resque to sidekiq and I missed one little thing (well, maybe two little things to be exact) - API methods `enqueue_to_in` and `enqueue_in` (if you used [resque-scheduler][1] before you will miss them). What do you think about adding them to sidekiq?

Cheers
[1]: https://github.com/resque/resque-scheduler