InsightToolkit : 4.4.2 and added python wrapping

- Added vtk dependency
- Added itkv3 compatibility option
- Changed the compiler to llvm-gcc
- Added a patch for ITK 4.4.2, so it can build with VTK 6.0.0 while ITKVtkGlue is set to ON
insighttoolkit: Try to remove llvm-gcc