Code change to prevent serial interface from becoming stuck perpetually due to stray characters during startup.
Added arlobot_safety package to monitor AC power on laptop and shut down motors if the ArloBot is plugged in. Override is possible with settings in encoders.yaml
AC Power connection shuts down motors and resets the Propller board now. Last position is saved in propeller_node so that propeller broadcasts last position if it is reset. This also allows us to send any position to initialize at.