message: ftp: parse ack for reset
  Without this we will timeout the reset because we don't parse the ack.
diff: @@ -96,6 +96,13 @@ void FtpImpl::_process_ack(PayloadHeader* payload)
  _call_op_result_callback(_session_result);
  break;
  + case CMD_RESET_SESSIONS:
  + _curr_op = CMD_NONE;
  + _session_valid = false;
  + _stop_timer();
  + _call_op_result_callback(_session_result);
  + break;
  +
  case CMD_LIST_DIRECTORY: {
  bool added = false;
  uint8_t start = 0;
  