Alan, they still go in app/codeapp/code. Make sure you have a registration.phpregistration.php in the modulename folder containing the following:
<?php \Magento\Framework\Component\ComponentRegistrar::register( \Magento\Framework\Component\ComponentRegistrar::MODULE, 'Namespace_Modulename', __DIR__ ); Then run:
php bin/magento setup:upgrade Just tested on fresh Magento 2 CE release and works properly.