Rails 5 support

[karensg]

Hi @fnando,

Great library! I have been using it for months without any problems. Rails 5 has just been released. It would be awesome to support it as well. There are very little breaking changes.

Karens

[YoonjaeYoo]

I want it too.

[unfernandito]

https://github.com/goalkeeper112/coupons

I forked this gem and fixed some features to add Rails 5 support, try and told me any issue

[YoonjaeYoo]

@goalkeeper112 Fantastic!

[grothier]

Hi @unfernandito ! is it now working for rails 5.0.3? I don't know how I should point to your forked repo in my gemfile, any advice? Thanks a lot!

EDIT: I made it point to your repo and it seems to work! thanks a lot!!