message: Enable connect over serial
diff: import serial
  from serial.tools import list_ports
  import contextlib
  +import os
  DRIVER_ACK = b'ok\r\nok\r\n'
  RECOVERY_TIMEOUT = 10
  DEFAULT_SERIAL_TIMEOUT = 5
  DEFAULT_WRITE_TIMEOUT = 30
  +# Note: FT232R is the board id for communication over usb on UNIX systems.
  +# This is set for serial communication in the Dockerfile
  +smoothie_id = os.environ.get('OT_SMOOTHIE_ID', 'FT232R')
  +
  ERROR_KEYWORD = b'error'
  ALARM_KEYWORD = b'ALARM'
  @@ -91,10 +96,11 @@ def write_and_return(
  return response
  -def connect(device_name, baudrate):
  +def connect(device_name=smoothie_id, baudrate=115200):
  '''
  Creates a serial connection
  :param device_name: defaults to 'Smoothieboard'
  + :param baudrate: integer frequency for serial communication
  :return: serial.Serial connection
  '''
  smoothie_port = get_ports(device_name=device_name)[0]
  