add more xmlnamespaceurl

[luckmoshy]

how about xsl plus adding more xml namespaceurl like

` // Start the URLset element

    $xml->startElement('urlset');
    $xml->writeAttribute('xmlns', 'http://www.sitemaps.org/schemas/sitemap/0.9');
    $xml->writeAttribute('xmlns:xsi', 'http://www.w3.org/2001/XMLSchema-instance');
    $xml->writeAttribute('xsi:schemaLocation', 'http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd');

$this->document->createProcessingInstruction('xml-stylesheet', 'type="text/xsl" href="stylesheet.xsl"');
`