Fix no exit lane case at the end

[Agustin Alba Chicar]

In some cases, for example in road 12 next to the perimeter zone of Darpa sample, the box reaches the last waypoint and the it turns to the right and continues at constant speed with no direction. We should fix this case by keeping the vehicle in its place with no motion.

[Michel Hidalgo]

After some discussion, we agreed that we should be dealing with this case at a higher, path planning level. Also, this isn't a high priority issue. We'll delay a fix until then.