ADD: GammaMap filter (SAR)

...les/Filtering/ImageNoise/include/otbGammaMAPImageFilter.h

...s/Filtering/ImageNoise/include/otbGammaMAPImageFilter.txx

Modules/Filtering/ImageNoise/test/CMakeLists.txt

Modules/Filtering/ImageNoise/test/otbGammaMAPFilter.cxx

...les/Filtering/ImageNoise/test/otbImageNoiseTestDriver.cxx