Change jupyter homedir, docker build documentation

[stoeps13]

changing the jupyter root directory to /home/jupyter (/ is writeprotected for user jupyter). Add some infos about building the docker image.

[wtnb75]

sorry for late release.
from selenible-0.0.3, kernelspec path is /usr/lib/python3.6/site-packages/selenible/seleniblepiter

I think other fixes (creating user, changing directory, image layer optimization, ...) are good.

[stoeps13]

Need to finish some work, but will change the path.

Now docker build is way better and the kernel is present. Need to add the chrome driver to test with the example iypnb