"BUG: fix missing ITCopyright.txt"

Following remarks from debian packagers, the ITCopyright.txt was mentioned in
several files but not available in the Copyright directory.  After contacting
the contributor Gregoire Mercier, he has suggested to harmonize the copyright for his
contributions.  Files with GET or IT copyright referenced now the
IMTCopyright.txt file (Institut Mines Telecom) which was added to the Copyright directory.

Moreover, Gregoire Mercier confirmed that he is not the author of 7 files which
are mentioning the GET or IT copyright:

Modules/Filtering/Projection/include/otbROIdataConversion.h
Modules/Filtering/Projection/include/otbROIdataConversion.txx
Modules/Segmentation/Conversion/test/otbVectorDataRasterizeFilter.cxx
Modules/Segmentation/Conversion/test/otbVectorDataToLabelImageFilterWithoutReader.cxx
Modules/Segmentation/Conversion/test/otbPolygonizationRasterizationTest.cxx
Modules/Segmentation/Conversion/test/otbVectorDataToLabelImageFilter.cxx
Modules/Segmentation/Conversion/test/otbOGRDataSourceToLabelImageFilter.cxx

Thus, the copyright was also modified for these 7 files (CNES Copyright).