Update DefaultWayPropertySetSource to treat CAR and CUSTOM_MOTOR_VEHICLE identically 

Treat CAR and CUSTOM_MOTOR_VEHICLE identically by default. Only users who want to configure a CUSTOM_MOTOR_VEHICLE should differentiate between the two.

Also -- use clearer, more consistent naming in StreetTraversalPermission.java than the recent patch used. Update StreetTraversalPermissionTest.java to test the new hybrid modes behavior. 

Avi