make a script to make dat files from CSVs

[chadwhitacre]

This is for #3.

[chadwhitacre]

Working through this with @kaguillera. We've got CSVs for New Alliance all ready to go. We're going to need CSVs for Stripe and Gratipay before we can finish writing and run this for 2012-07 (#2). Stripe CSVs will be pretty easy to get. However, Gratipay CSVs are blocked on gratipay/gratipay.com#2779. 😧

[chadwhitacre]

Stripe logs done in https://github.com/gratipay/logs/commit/15d55ce926d46eafec419ef482d4eae7ad73c027.

[techtonik]

What is manual input and output?

[chadwhitacre]

From #31 (comment):

@kaguillera I started a script in 828840f to spit out Ledger-formatted entries from a CSV. I think actually what we want is a script to take info for an individual entry on the command line and spit out a single entry for Ledger, and then additional scripts that use the one-off script for multiple entries as needed.