whitespace
Fix custom fields application

xhr was not in scope. xdr was intended. This is fixed.
Using $.extend() means we do not have to specify each field.
Renamed xhrFields to xdrFields. As this is what they are.
Fomerly, property names were unnecessarily translated:
	xhrFields.error -> xhr.onerror
	xhrFields.timeout -> xhr.ontimeout
Now there is no translation, use the exact names:
	xdrFields.onerror -> xdr.onerror
	xdrFields.ontimeout -> xdr.ontimeout
Merge pull request #1 from infoxchange/xhrfields-fix

Xhrfields fix