Changed printout to include help message

src/c/CudaMex/AddConstant.cpp

src/c/CudaMex/AddImageWith.cpp

src/c/CudaMex/ApplyPolyTransformation.cpp

src/c/CudaMex/CudaMex.cpp

src/c/CudaMex/GaussianFilter.cpp

src/c/CudaMex/MeanFilter.cpp

src/c/CudaMex/MedianFilter.cpp

src/c/CudaMex/MexCommand.h

src/c/CudaMex/ReduceImage.cpp