Added uav_auto_mode.py

uav_auto_mode.py should probably be merged with main.py later. Currently
sends a message through serial to Arduino, signaling when the altitude
is 60000 ft. However, the code is incomplete and won't run in the
current state.
Added small_demo.py (uses DroneAPI)

Changes to original file:
import serial (line 11)
write to serial when altitude == 18000 m (lines 31-41), still missing
communication protocol