replace class_inheritable_attribute with class_attributes (it's deprecated in ActiveSupport 3.1)
… deprecated in Rails 3.1
… the base class but is extended in, so the check has been changed to just make sure model_name has been implemented
… 1.9 behave differently) which fixes a test
…ctiveRecord as a dependency and instead adding the requirement of ActiveModel, also bundler has been added for development and development dependencies have been specified.