Make MEDINRIA_TEST_DATA_ROOT non mandatory.
Make MEDINRIA_TEST_DATA_ROOT non mandatory.

aabadie/medInria-public,NicolasSchnitzler/medInria-public,NicolasSchnitzler/medInria-public,NicolasSchnitzler/medInria-public,aabadie/medInria-public,rdebroiz/medInria-public,aabadie/medInria-public,rdebroiz/medInria-public,rdebroiz/medInria-public