Cleanups and instructions to improve portability

Hello New York Times,

Thank you for publishing the model and data for your new poll aggregator project. This is really wonderful from a reproducibility and robustness standpoint, and I hope some of your competitors (e.g. Votamatic and 538) will follow your lead.

My colleagues and I worked on a similar system at the MIT student newspaper during the runup to the 2004 presidential election (http://web.mit.edu/keithw/monte/), and I understand that in the quantitative social sciences, releasing a replication package is now a minimum requirement to publication. (E.g. https://www.aeaweb.org/aej/data.php .) It is great to see a national newspaper do this right.

Here are some cleanups that allow the code to run on a case-sensitive filesystem (e.g. something other than Mac OS X) and get rid of some latent dependency on the directory structure used on the authors' computers.

I am curious how you intend to update the polling data -- will there simply be a new commit to this repository every day, updating the polls?

Thank you again,
Keith