SSH to user's coffea-casa JupyterHub session

[oshadura]

Test access through ssh to coffea-casa JupyterHub, using https://github.com/yuvipanda/jupyterhub-ssh

How it will work:

The JupyterHub SSH service provides SSH access to your user environment in a JupyterHub. JupyterHub SSH is made up of two main components:

• an SSH server that maps a SSH connection to a Notebook server on a JupyterHub.
• a Terminado client that knows how to connect and communicate to a Jupyter terminal.