Test using turbolinks master

See
https://github.com/rails/turbolinks/commit/153f1b0f04c718442cfd73365a2778dfe1a1c5c7

Gemfile

@@ -10,7 +10,7 @@ gem 'mocha', '~> 0.14', require: false
 gem 'rack', github: 'rack/rack'
 gem 'rack-cache', '~> 1.2'
 gem 'jquery-rails', '~> 3.1.0'
-gem 'turbolinks'
+gem 'turbolinks', github: 'rails/turbolinks', branch: 'master'
 gem 'coffee-rails', '~> 4.0.0'
 gem 'arel', github: 'rails/arel', branch: 'master'
 gem 'sprockets-rails', github: 'rails/sprockets-rails', branch: 'master'