Added an example upload with tutorial and notebook.

dependencies/nomad-remote-tools-hub

examples/data/cow_tutorial/README.md

examples/data/cow_tutorial/Tutorial.ipynb

examples/data/cow_tutorial/countriesplugin/__init__.py

...ples/data/cow_tutorial/countriesplugin/example.nomad.yaml

examples/data/cow_tutorial/countriesplugin/nomad_plugin.yaml

examples/data/cow_tutorial/countriesplugin/parser.py

examples/data/cow_tutorial/countriesplugin/schema.py

examples/data/cow_tutorial/nomad_data/.empty

examples/data/cow_tutorial/raw_data/France.data.txt

examples/data/cow_tutorial/raw_data/Germany.data.txt

examples/data/cow_tutorial/raw_data/Poland.data.txt

examples/data/uploads/example_uploads.yml

gui/src/components/north/NorthTool.js

gui/tests/artifacts.js

gui/tests/env.js

nomad/app/main.py

nomad/app/v1/routers/north.py

nomad/client/processing.py

nomad/config/north.py