get_samples implemented, tests added

src/python/PyBis/pybis/__init__.py

src/python/PyBis/pybis/pybis.py

src/python/PyBis/pybis/pybis_test.py

src/python/PyBis/pybis/scripts/cli.py

src/python/PyBis/setup.py

src/python/pybis/tests/conftest.py

src/python/pybis/tests/test_imports.py

src/python/pybis/tests/test_openbis.py