Run notebook on Travis

[hadim]

Both Travis and CircleCI randomly fail when running notebooks. The code has then been commented: https://github.com/hadim/scijava-jupyter-kernel/blob/master/.ci/test.sh

If someone can make it work, that would be awesome :-)

See also this jupyter/nbconvert#581

[hadim]

Test.ipynb is executed. It's very minimal but it's better than nothing.

[hadim]

It still randomly fail even with one notebook to run.

[hadim]

could #57 help with that ?

[hadim]

It makes me cry each time I see this issue. I'll close in favor of #58