Merge branch 'release/pybis-1.8.3'

pybis/src/python/CHANGELOG.md

pybis/src/python/README.md

pybis/src/python/README.rst

pybis/src/python/pybis/__init__.py

pybis/src/python/pybis/attribute.py

pybis/src/python/pybis/definitions.py

pybis/src/python/pybis/pybis.py

pybis/src/python/pybis/utils.py

pybis/src/python/setup.py

pybis/src/python/tests/test_dataset.py

pybis/src/python/tests/test_sample.py