Use thin as default server

spec/support/capybara.rb

@@ -10,6 +10,12 @@ Rails.application.config do
   config.middleware.use RackSessionAccess::Middleware
 end
 
+Capybara.register_server :thin do |app, port, host|
+   require 'rack/handler/thin'
+   Rack::Handler::Thin.run(app, :Port => port, :Host => host)
+end
+Capybara.server = :thin
+
 Capybara.register_driver :selenium do |app|
   require 'selenium/webdriver'