ENH: Remote module capability

An implementation of Remote modules. This approach follows the ITK implementation.

Three remote modules are included for testing David Doria's Poisson Reconstruction, David Gobbi's vtkDICOM and Slicer's vtkAddon.

To configure vtk with these remote modules: cmake -DvtkAddon:BOOL=ON -DModule_PoissonReconstruction:BOOL=ON -DModule_vtkDICOM:BOOL=ON vtk_source_dir make