Support them all (bring rails 4.1.0 and edge development to master)

Hi there guys

This is a working in progress. Right now `huoxito:all-rails` branch should have support for both rails 4.0.x and rails 4.1.x.

I branched off `rails-4` then merged `rails-4-1` into it. Next my idea is to merge `activerecord-hackery:master` into `huoxito:all-rails` and work from there until you can do a safe and easy merge back to upstream master.

Before I move on with it I just wanted to confirm again that the goal is having Ransack master branch supporting all rails versions back to 3.0.x? I believe we can do that for sure but honestly it sounds easier to create a new branch off master, e.g. `rails-3-stable`, and only support latest 3 or possibly 2? rails versions, e.g. ransack master could support only rails 4.1, 4.0 and 3.2.

Let me know what you guys think? Hopefully we can get things done today or tomorrow.

// @jonatack @radar