Fixed issue in _xmlEncode: only replace &, < and > in case the value argument is a string, otherwise, just pass on the value as is (and rely on implicit string conversion by caller).
Fixed issue in _xmlEncode: only replace &, < and > in case the value argument is a string, otherwise, just pass on the value as is (and rely on implicit string conversion by caller).

Spotted by James Dixon, pentaho corporation. Thanks James! 

ishaigor/xmla4js,ishaigor/xmla4js,rpbouman/xmla4js,rpbouman/xmla4js,ishaigor/xmla4js,rpbouman/xmla4js