Patch to allow ActiveRecord's find to take a Range of IDs

Hi.

I have a patch that will let find to take a Range of IDs. This will allow you to do `Person.find(5..10)` or `Person.find(1, 6..11)`.

https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/3419-allow-activerecords-find-to-take-a-range

Thanks.
Mike