Rethink gadi_jupyter

[ScottWales]

Having gadi_jupyter as a bash script is becoming unweildy. Consider splitting into two halves - a frontend written in bash (for portability) that users run on their own computer, and a backend written in python that runs on gadi that does the actual queue submission.

This would allow us to handle things like resources for different queues in a more sensible language

[aidanheerdegen]

I like the idea, but wonder if @jmunroe's jupyter hub concept would be a better alternative.

James, is there a repo/script we can have a play with?