Merged requested to merge north-api into 922-customising-jupyterhub-deployment-named-servers-and-volumes-2
Added a north API that replaces nomad logic in jupyterhub and nomad GUI.
- moves responsibility from north GUI into a new north API that now list, starts, and stops tools
- jupyterhub becomes independent from nomad code as all nomad specific tasks are done in the new north API
- north API uses jupyterhub service to authenticate, no user tokens required anymore