public function register(\Silex\Application $app)
    {
        parent::register($app);

        // Register voters
        $app->extend('security.voters', function($voters) {
            return array_merge($voters, $this->voters);
        });

        // Add reference to this in application instance
        $this->app = $app;
        $this->app['securilex'] = $this;
    }