Add local resources to Bolt translations

gistfile1.php

<?php 
namespace MySite\Bolt\Provider;

use Silex\ServiceProviderInterface;
use Silex\Application;
use Symfony\Component\Translation\Loader\YamlFileLoader;

/**
* 
*/
class Translations implements ServiceProviderInterface
{
    public function register(Application $app)
    {
            
    }

    public function boot(Application $app)
    {

        $app['translator'] = $app->share(
            $app->extend(
                'translator',
                function ($translator, $app) {
                    $translator->addLoader('yaml', new YamlFileLoader());
                    $path = $app['resources']->getPath('root/app/resources/translations/fr_FR');
                    $translator->addResource('yaml', $path.'/messages.yml', 'fr_FR');
                    return $translator;
                }
            )
        );
    }
}