Add support for being used with sbot_simulator

[WillB97]

• Adds support for the sbot_simulator method of attaching to boards over socket, instead of serial port.
• Adds support for remote sleep control to allow the the robot to sleep for periods of simulator time.
• Adds support for loading metadata from a file whose path is passed through an environment variable.
• Adds a WebotsRemoteCameraSource to receive camera frames over a socket.
• Adds ultrasound support to arduino.

Built for use with the SR fork: https://github.com/srobo/sbot_simulator

[8BitJosh]

Basic test in simulator and on a physical kit and all looks good