private function registerDefaultWebLoaders()
    {
        if (function_exists('curl_init')) {
            $this->loaders['https'] = new CurlWebLoader('https://');
            $this->loaders['http']  = new CurlWebLoader('http://');
        } else {
            $this->loaders['https'] = new FileGetContentsWebLoader('https://');
            $this->loaders['http']  = new FileGetContentsWebLoader('http://');
        }
    }