Do not parse ATIS responses if lines are not enabled

See Issue jankolkmeier#37. When using the ParseIOSamplePayload function to parse Payload to on packages from nodes with disabled IO lines it will break. Checking the commandStatus of the AT response fixes this.

lib/frame-parser.js

@@ -203,6 +203,9 @@ frame_parser.parseNodeIdentificationPayload = function(frame, reader) {
 frame_parser.ParseIOSamplePayload = function(frame, reader) {
  frame.digitalSamples = {};
  frame.analogSamples = {};
+ frame.numSamples = 0;
+ // When parsing responses to ATIS, there is no data to parse if IO lines are not enabled
+ if (frame.commandStatus !== undefined && frame.commandStatus !== 0) return;
  frame.numSamples = reader.nextUInt8();
  var mskD = reader.nextUInt16BE(); 
  var mskA = reader.nextUInt8();