[fix] handle missing url scheme - fixes #428

    # parse results

    for result in dom.xpath(results_xpath):

        url = result.xpath(url_xpath)[0].text

        if not url.startswith('http://') and not url.startswith('https://'):

            url = 'http://' + url

        title = result.xpath(title_xpath)[0].text

        content = escape(result.xpath(content_xpath)[0].text)