Script to synchronize payments with a CSV

Adds a management script which takes a csv file name argument. Based on the values in the associated csv, transactions are deleted and fund amounts are updated.

Adds timezone configuration info (though we encourage UTC for everything).

Uses `round` when multiplying to turn dollars into cents to avoid annoying floating point issues.
Where are these CSV files coming from?

In my previous experience with python's csv lib, I ran into some trouble with certain csv dialects detecting new lines and different fields correctly. Are all the csvs uploaded going to be from the same program?