Merge pull request #29 from jamesmccann/intersection_example

Four way junction example
Added actuated traffic control features, min and max green times, and gap timer
Added display of current controller phase times to sim
Merge branch 'feature/vehicle_actuated_traffic_control' into vehicle_priority3
Updated junction example to use actuated control
Merge branch 'feature/vehicle_actuated_traffic_control' into vehicle_priority3
Added urgency to draw vehicle