Fix build in ruby 1.8.7

gemfiles/Gemfile-ruby-1.8.7

@@ -4,6 +4,7 @@ gem 'activesupport', '~> 3.2'
 gem 'nokogiri', '~>1.5.11'
 gem 'mime-types', '~>1.16'
 gem 'rest-client', '~> 1.6.7'
+gem 'i18n', '~> 0.6.11'
 
 group :development, :test do
   # This is here because gemspec doesn't support require: false