updating to support all rails versions 3.0+
Merge pull request #23 from felafelwaffle/master

Relax pinned rails dependencies so that gem works with all 3.x and above rails versions
Merge pull request #24 from dhruvasagar/master

Added #where to base.rb
prefer calling actual rails callbacks API method over private rails method
Merge pull request #25 from felafelwaffle/felafelwaffle-rails-4-support

Rails 4 compatibility