uRemote initilization for EV3

[ste7anste7an]

• check if EV3 by:

import sys
EV3 = (str(sys.implementation).find('EV3')>0)

• if EV3, then remove power_pin parameter from UARTDevice
• if using LMS-EV3-breakout board :
  • if EV3, add option to choose external power from motor port