Make starter restart correctly on pi's

This configures systemd much better so it automatically restarts and
gets the kill signals right.

Change-Id: I43576758f1b137ca24ad1ee960dd8715143aa7e6
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/aos/starter/starter.sh b/aos/starter/starter.sh
index 2c8494e..2db812a 100755
--- a/aos/starter/starter.sh
+++ b/aos/starter/starter.sh
@@ -8,8 +8,9 @@
   ln -s /var/local/natinst/log/FRC_UserProgram.log /tmp/FRC_UserProgram.log
   ln -s /var/local/natinst/log/FRC_UserProgram.log "${ROBOT_CODE}/FRC_UserProgram.log"
 elif [[ "$(hostname)" == "pi-"* ]]; then
-  ROBOT_CODE="/home/pi/robot_code"
-
+  # We have systemd configured to handle restarting, so just exec.
+  export PATH="${PATH}:/home/pi/robot_code"
+  exec starterd
 else
   ROBOT_CODE="${HOME}/robot_code"
 fi