ENH: Update minimum required version of CMake from 2.8.8 to 3.3
ENH: Update minimum required version of CMake from 2.8.8 to 3.3

The version now match the one used in VTK 8.1

lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples