Dac 524 baseline v2, v3, NLU demo

[TimeaBagosiCrim]

final NLU module containing V1, V2, V3, Demo notebook, evaluation, stac handler, etc.

[TimeaBagosiCrim]

new requirements to be added
it needs a Docker service to be run: rasa/duckling on port 8000
it needs prop_vdb and target_vdb directories (committed here but can be rolled back if placed somewhere else)
question: absolute paths in many files, replace them with what?

[fmigneault]

Since the files are provided as demo samples, all JSON contents should probably be reformatted with newlines to make them more readable
(can use cat "<file.json>" | jq > "<file.json>" to indent them).

[fmigneault]

@TimeaBagosiCrim
If added a new way to call duckling that does not require the docker image in 0d93ef7. It uses a pre-installed binary instead.

I found a few places where V2 pipeline was broken with missing VDB instance references.
After fixing those, I reached a point where V3 pipeline tries to obtain spans from V2 pipeline, which always causes an error.
This can be seen in https://github.com/crim-ca/pavics-jupyter-images/blob/DAC-524-baseline-V2/nlp/notebooks/NLU_demo.ipynb
Do you have an idea on how this can be fixed?