stop() {
    if (this.isRecording) {
      return this.stopRecording();
    }

    return new Promise((resolve, reject) => {
      this.player.stop();

      resolve(this.mp3);
    });
  }
Stops recording audio if Micron is recording, if not
just pauses the player and set's the currentTime to 0.

@example
  microm.stop().then(function(mp3) {
   console.log(mp3.url, mp3.blob);
  });
  
@return {Promise} Will be resolved with the mp3.