thoughtbot/refills — pull request #51 by tchopoorian (2014-04-07 19:08:51+00:00)
Title: require 'rails/generators' in list_generator.rb'

See closed pull request #33. I was getting the same "uninitialized constant Rails::Generators (NameError)" when trying the list generator, so I added the same require to list_generator.rb. That seems to have solved it.