Merge pull request #1287 from owncloud/ocs_xml_attributes

API: Treat array keys starting with '@' as XML attributes

lib/api.php

@@ -188,7 +188,10 @@ class OC_API {
 
 	private static function toXML($array, $writer) {
 		foreach($array as $k => $v) {
-			if (is_numeric($k)) {
+			if ($k[0] === '@') {
+				$writer->writeAttribute(substr($k, 1), $v);
+				continue;
+			} else if (is_numeric($k)) {
 				$k = 'element';
 			}
 			if(is_array($v)) {