Updates for future potential python 3 version

orekit-conda-recipe/meta.yaml

orekit-conda-recipe/pyhelpers.py

orekit-conda-recipe/run_test.sh

orekit-conda-recipe/test/AbstractDetectorTest.py

orekit-conda-recipe/test/AltitudeDetectorTest.py

orekit-conda-recipe/test/BackAndForthDetectorTest.py

orekit-conda-recipe/test/EventDetectorTest.py

orekit-conda-recipe/test/EventHandlerTest.py

orekit-conda-recipe/test/GroundFieldOfViewDetectorTest.py

orekit-conda-recipe/test/ImpulseManeuverTest.py

orekit-conda-recipe/test/KeplerianConverterTest.py

orekit-conda-recipe/test/NodeDetectorTest.py

orekit-conda-recipe/test/SmallManeuverAnalyticalModelTest.py