Ensure that jbuilder is loaded correctly

If JBuilderTemplate class was loaded before JBuilder then the
superclass for the template would be a proxy object class and
not the full JBuilder class.

Author: pixeltrix

test/test_helper.rb

@@ -2,6 +2,7 @@
 require "active_support"
 require 'active_support/core_ext/array/access'
 require "rails/version"
+require "jbuilder"
 
 if Rails::VERSION::STRING > "4.0"
   require "active_support/testing/autorun"