modify to be deployable on pypi

Pypi feedstock for blissdata: https://gitlab.esrf.fr/denolf/blissdata/

Pypi release (0.1.0b): https://pypi.org/project/blissdata/

This MR makes the required changes needed for the pypi release.

You can now do this in any python environment:

pip install blissdata[test]
pytest --pyargs blissdata