Upgrade Jupyter Notebooks

The Jupyter notebooks service has been upgraded. This upgrade included a number of stability and security fixes.We also integrated JupyterLab, which is the next-generation user interface for the Jupyter project. By default, all users now end up in this new user interface. JupyterLab offers the same features as the classic Jupyter interface, but in a flexible and more powerful user interface, allowing a user to organize the layout and resize the tabs. By default it also includes support to render different file types, like large CSV files. We also included support for the Python36 interpreter, which is now the default interpreter for Python 3.