fix for defaults layout

Hi. I commit a simple tests t/lite_app_with_default_layouts.t as in https://github.com/fayland/mojox-renderer-tt/commit/95d9ee5c356fa3f398b2deed9611ba47b69a890b

`app->defaults(layout => 'wrapper');`

then every template is just returning the content in the wrapper.html.tt
'WS--EW'

the [% content %] got lost.

I provide a patch too but not sure if that's a correct fix or not. please take a look and let me know if you can fix it in other way, or tell me I'm using the plugin in a wrong way.