Update to FSL default and minimal example for vizualization

[cmaumet]

@remiadon - this PR includes a few edits to your fsl_default.json file as well as a notebook test_diplay_graphs.ipynb with code snippets to vizualize our PROV JSON-LD 1.1 document.

For examplefsl_default.json is vizualized as:

Hopefully this will help in refining and building more examples 🎉

[remiadon]

@cmaumet that's really awesome 😀

[remiadon]

@cmaumet the notebook is exactly what I was looking for,
I'll wrap your functions into a CLI for automated display of the graphs we generate, and try it on the SPM example

[remiadon]

TODO
Sub-divide "Stats" activity into "film_gls" and "smoothness"
see this log file