Rename cpp files in Examples/ITK folder

Simplify CMake code Fix #45
Simplify CMake Code for VTK examples
rename vtk*.cxx -> vtk*.cpp
Merge branch 'travisAllBranches' into ExamplesCMakeForLoop
remove ITK_STATISTICAL_MODEL_INCLUDE_DIR
fix cmake error
missing space in target_link_libraries call
itkBuildImageIntensityModelOnROI does not compile
Merge pull request #65 from statismo/ExamplesCMakeForLoop

Rename cpp files in Examples/ITK folder