ConsumerStream.prototype._read fires when this.active === false

[joelnet]

I have implemented a Consumer from https://github.com/confluentinc/kafka-rest-node/blob/master/examples/console_consumer.js

Occasionally I am getting a 500 error when shutting down.

20:37:50.226Z  INFO: Attempting to shut down consumer instance...
20:37:50.333Z  INFO: Consumer stream closed.
20:37:50.350Z  INFO: Consumer instance closed.
20:37:50.351Z  INFO: Consumer has shut down.
20:37:50.353Z ERROR: Consumer instance reported an error: { error_code: 500, message: 'Internal Server Error' }
20:37:50.353Z  INFO: Attempting to shut down consumer instance...

Logs from kafka-rest also show a DELETE happens, then a GET happens.

[2017-06-01 20:46:39,625] INFO 127.0.0.1 - - [01/Jun/2017:20:46:39 +0000] "DELETE /consumers/mytopic-consumer-1496349998/instances/rest-consumer-4820caa6-d67d-4588-95ff-072c251d59a3 HTTP/1.1" 204 0  14 (io.confluent.rest-utils.requests:77)
[2017-06-01 20:46:39,628] INFO 127.0.0.1 - - [01/Jun/2017:20:46:39 +0000] "GET /consumers/mytopic-consumer-1496349998/instances/rest-consumer-4820caa6-d67d-4588-95ff-072c251d59a3/topics/mytopic HTTP/1.1" 500
 52  17 (io.confluent.rest-utils.requests:77)

During debugging of ConsumerStream, I noticed _read will fire after a shutdown. this.active is set to false, but the client request is still sent which results in a 500 error.

[joelnet]

I have submitted a pull request here: #30