OAI no longer distributes `contents.csv` files

[soupault]

The contents.csv files, which provide followup-wise imaging data indices, seem no longer to be a part of the OAI (cannot be found on the website). These files were used in entry/Targets_meta_and_scans_from_OAI.ipynb (3rd cell) to perform imaging data selection and extraction from the complete database.

For reference, here is a header of contents.csv from 00m:

The code needs to be refactored to account for the new structure of the OAI database.