Patch for assert_templates

Hello,

I believe that I have fixes assert_template to properly assert that a

certain layout is being rendered by a controller action. Before this patch

I believe that the code was not even being run by the tests and hence not

properly checking for layouts in tests.

Here is a link to the Lighthouse ticket:

https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/5247

Thanks, Mike