silence cucumber's require outside of necessary files

Gemfile

@@ -13,7 +13,7 @@ group :development, :test do
 end
 
 group :test do
-  gem 'cucumber-rails'
+  gem 'cucumber-rails', :require => false
   gem 'cucumber-rails-training-wheels'
   gem 'database_cleaner'
   gem 'capybara'