I would love any documentation/article/lead to help running and supporting older rails versions. I've published a gem that supports both rails-4 and rails-3 (https://github.com/oelmekki/activerecord_any_of), but it supports only rails-3.2.13 for the 3.x part as it is my current installed version. I would rather support at least all 3.2.x branch.

And thank you for contributing in making rails awesome :)