fix bitBucket for RecognizeMic keepMic option

Author: nfriedly

dist/watson-speech.js

@@ -22,10 +22,17 @@ var L16 = require('./webaudio-l16-stream.js');
 var FormatStream = require('./format-stream.js');
 var assign = require('object.assign/polyfill')();
 var WritableElementStream = require('./writable-element-stream');
-var Readable = require('stream').Readable;
+var Writable = require('stream').Writable;
 
 var preservedMicStream;
-var bitBucket = new Readable();
+var bitBucket = new Writable({
+  write(chunk, encoding, callback) {
+    // when the keepMicrophone option is enabled, unused audio data is sent here so that it isn't buffered by other streams.
+    callback();
+  },
+  objectMode: true, // can still accept strings/buffers
+  decodeStrings: false
+}); 
 
 /**
  * @module watson-speech/speech-to-text/recognize-microphone