Update Dockerfile with latest commit

[sharky93]

Updated the docker image on the sci-py server which now includes matplotlib by default and sets it to the 'agg' mode.

Need to update the Dockerfile with the changes so that fresh installs can function the same way

[stefanv]

Can you describe which changes are needed so that we don't lose track of this?

[sharky93]

The change which enables running a Python user-script every time the interpreter is initialized