Fix raw template being returned by SingleLogoutResponse.php (#1192)
Fix raw template being returned by SingleLogoutResponse.php (#1192)

* Force template to be rendered by Twig

simplesamlphp/simplesamlphp,ghalse/simplesamlphp,simplesamlphp/simplesamlphp,simplesamlphp/simplesamlphp,simplesamlphp/simplesamlphp,dnmvisser/simplesamlphp,dnmvisser/simplesamlphp,dnmvisser/simplesamlphp,ghalse/simplesamlphp,dnmvisser/simplesamlphp,ghalse/simplesamlphp,ghalse/simplesamlphp