Clean up folder structure

[haesleinhuepf]

I think we should clean up our folder structure. This repository served as a quick prototype initially and now becomes more and more an infrastructure.

Short-term proposal:

• Move all notebooks which analyse / visualize some data into the notebooks folder.

Mid-term proposal:

• All infrastructure for reading/writing/modifying our database go in a separate repository. This repository should be a pip-installable Python package. Before doing this, we should have a wage idea about our target API.
• Our website repository pip-installs the infrastructure repository and uses functions from there. It does not contain any python code in .py files. Notebooks in this repository serve demonstration purposes only, and do not modify the database and/or visualizations.