Avoid loading responses (and templates) lazily as they need to be registered in time

Signed-off-by: Josep M. Blanquer <blanquer@rightscale.com>
Fixed 404 handling in app generator.

Return 404 instead of 500 for show action on unknown resource id.

Signed-off-by: Magne Land <magne.land@appfolio.com>
Skip response_template block after rebasing fix from master.

Signed-off-by: Magne Land <magne.land@appfolio.com>