Organize data files

[davewhipp]

We should organize the data files into a single package that could be versioned and hosted on Zenodo. The following things would be helpful for this:

• Compiling a list of all of the data files we need
• Creating a directory containing all data files such that they can be extracted in the base book directory and find the correct locations for the notebooks to work
• Creating a table of data files with download links for individual book notebooks