Fixed drawing a cube and a circle with vtk 6.x

It was missing a call to tf->Update() when creating certain shapes.
See this forum post for more information.
http://www.pcl-users.org/Drawing-a-cube-td4034458.html#a4035128
Fix compile for CUDA and VTK 6 for gpu_people module.
Merge pull request #873 from dirklanger/master

Fixed drawing a cube and a circle with vtk 6.x
Merge pull request #876 from yangyanli/fix_vtk6_cuda_compile

Fix compile for CUDA and VTK 6 for gpu_people module.