Merge branch 'feature/vocabularies' into develop

src/python/PyBis/README.md

src/python/PyBis/pybis/attribute.py

src/python/PyBis/pybis/definitions.py

src/python/PyBis/pybis/pybis.py

src/python/PyBis/pybis/space.py

src/python/PyBis/pybis/things.py

src/python/PyBis/pybis/utils.py

src/python/PyBis/pybis/vocabulary.py

src/python/PyBis/tests/test_vocabulary.py

src/vagrant/jupyter-bis/README.md