Create test workflow for jupyter notebooks

[iulusoy]

• create CI that runs the jupyter notebooks
• try to set up workflow in a way that used resources are kept at a minimum (ie. not too many test images / queries)
• do not run the text detector in the CI since that requires a google API key: Either catch the exception in the demo notebook or create a separate notebook for multimodal search, and run only that notebook in the CI (preferred)