request.end([data][, encoding][, callback])
Finishes sending the request. If any parts of the body are unsent, it will flush them to the stream. If the request is chunked, this will send the terminating '0\r\n\r\n'.
If data is specified, it is equivalent to calling response.write(data, encoding) followed by request.end(callback).
If callback is specified, it will be called when the request stream is finished.