PHPDoc updates and one fix

if notify_stages is not define in config.yml then the report did not work! 

Because ```$config['notify_stages']``` is an empty array and this do not catch:

    if (is_array($config['notify_stages'])) {
        $container->setParameter('bugsnag.notify_stages', $config['notify_stages']);
    } else {
         $container->setParameter('bugsnag.notify_stages', array('staging', 'production'));
    }