Add support for Historical Data

[pedrocruzio]

In addition to the summary of cases, we should integrate the historical data as suggested by Danilo Pérez (@sanchobarriga).

What data structure should we use for this?

[sanchobarriga]

The CSVs pushed today worked perfectly for me, and continuing forward, the repository folder structure will facilitate historical search.

However, it would also be wise for there to be a static link to the most recent data to facilitate automated retrieval.

These suggestions are led by my experience working with the covidtracking.com project. If the current mode of operations is actually better and I just don't know how to work with it, feel free to say so, lol.