add options response as xhr issue OPTIONS first before PUT and DELETE
remove change res.send(200) to res.send(),
res.send(200) will add "OK" to response BODY, jQuery xhr  throw error to convert "OK" to JSON object, however setting type to jQuery ajax request's dataType to "Text" will not convert.
Not sure if this comply with the actual restful service implementation.
res.send() will not add "anything" to response body, but status is still "OK".