Add Apache licence boilerplate to all source/header files

src/classification/ConvexHull1D.cpp

src/classification/ConvexHull1D.hpp

src/classification/LPWrapper.cpp

src/classification/LPWrapper.hpp

src/classification/SVMWrapper.cpp

src/classification/SVMWrapper.hpp

src/classification/prop_sorted_d_mat.cpp

src/classification/prop_sorted_d_mat.hpp

src/descriptor_identifier/Model/Model.cpp

src/descriptor_identifier/Model/Model.hpp

src/descriptor_identifier/Model/ModelClassifier.cpp

src/descriptor_identifier/Model/ModelClassifier.hpp

src/descriptor_identifier/Model/ModelLogRegressor.cpp

src/descriptor_identifier/Model/ModelLogRegressor.hpp

src/descriptor_identifier/Model/ModelRegressor.cpp

src/descriptor_identifier/Model/ModelRegressor.hpp

src/descriptor_identifier/SISSO_DI/SISSOClassifier.cpp

src/descriptor_identifier/SISSO_DI/SISSOClassifier.hpp

src/descriptor_identifier/SISSO_DI/SISSOLogRegressor.cpp

src/descriptor_identifier/SISSO_DI/SISSOLogRegressor.hpp