Suggestion: in config world whitelist

First off, thank you for your work on ClickShop, it’s an awesome plugin.
I’d love to suggest a feature that could add even more flexibility: could you add to the config a list of worlds where it's possible to create a shop? This would allow players to place signs normally in the other worlds not included in the list, without needing to use shift.

Thanks for considering and keep up the great work!