Fixed a build by freezeing cucumber-expressions gem to a known working version.

features/step_definitions/rails_steps.rb

 Given /^I generate a new rails application$/ do
   steps %{
-    When I run `rails new #{APP_NAME} --skip-bundle`
+    When I successfully run `rails new #{APP_NAME} --skip-bundle`
     And I cd to "#{APP_NAME}"
   }
 

paperclip.gemspec

@@ -38,6 +38,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency('aws-sdk', '>= 2.3.0', '< 3.0')
   s.add_development_dependency('bourne')
   s.add_development_dependency('cucumber-rails')
+  s.add_development_dependency('cucumber-expressions', '4.0.3') # TODO: investigate failures on 4.0.4
   s.add_development_dependency('aruba', '~> 0.9.0')
   s.add_development_dependency('nokogiri')
   s.add_development_dependency('capybara')