COMP: VTK5 and VTK6 compatibility issues

-#include "vtkVersionMacros.h"
+#include "vtkVersion.h"

The file vtkVersion.h exists in both vtk5 and vtk6
to subsequently include the correct version numbers
for vtk.  vtkVersionMacros.h only exists in vtk6 and
was causing compilation failures for vtk5.