Populate cpp RigidBody contact_pts
Populate cpp RigidBody contact_pts

`constructModelmex` calls `getTerrainContactPoints` and passes those points
along to the c++ `RigidBody` objects.

hanssusilo/drake,billhoffman/drake,edowson/drake,tkoolen/drake,scottviteri/drake,billhoffman/drake,psiorx/drake,manuelli/drake,thientu/drake,billhoffman/drake,astrorog/drake,astrorog/drake,tkoolen/drake,thientu/drake,crogers3/drake,sheim/drake,crogers3/drake,scottviteri/drake,edowson/drake,hanssusilo/drake,psiorx/drake,scottviteri/drake,hanssusilo/drake,crogers3/drake,sheim/drake,astrorog/drake,sheim/drake,manuelli/drake,edowson/drake,hanssusilo/drake,sheim/drake,manuelli/drake,crogers3/drake,thientu/drake,billhoffman/drake,tkoolen/drake,scottviteri/drake,edowson/drake,psiorx/drake,edowson/drake,psiorx/drake,psiorx/drake,billhoffman/drake,tkoolen/drake,tkoolen/drake,astrorog/drake,edowson/drake,scottviteri/drake,astrorog/drake,sheim/drake,astrorog/drake,crogers3/drake,crogers3/drake,astrorog/drake,sheim/drake,crogers3/drake,scottviteri/drake,billhoffman/drake,sheim/drake,thientu/drake,edowson/drake,tkoolen/drake,hanssusilo/drake,edowson/drake,crogers3/drake,psiorx/drake,thientu/drake,hanssusilo/drake,hanssusilo/drake,manuelli/drake,psiorx/drake,psiorx/drake,sheim/drake,billhoffman/drake,scottviteri/drake,hanssusilo/drake,manuelli/drake,manuelli/drake,billhoffman/drake,thientu/drake,manuelli/drake,thientu/drake,tkoolen/drake