colomoto-docker.py should automatically launch browser

[pauleve]

It would be nice if the colomoto-docker.py script launches the browser once the docker has started.
It requires a bit of hacking though to detect when the jupyter service is ready.

[pauleve]

On linux

./colomoto-docker.py

will now launch browser when the docker has been started.

To be tested on macOS/windows, with the usual docker distributions, including Docker Toolbox
cc @aurelien-naldi @chernan