Add test-cases from ActiveSupport::Inflector
Add test-cases from ActiveSupport::Inflector

This will hopefully help make it harder to break something by accident.

Eric-Guo/ember-inflector,Eric-Guo/ember-inflector,stefanpenner/ember-inflector,grapho/ember-inflector,fivetanley/ember-inflector,jerel/ember-inflector,fivetanley/ember-inflector,greyhwndz/ember-inflector,stefanpenner/ember-inflector,greyhwndz/ember-inflector,jerel/ember-inflector,grapho/ember-inflector