CRITICAL: non-US date formats do not parse

[baeolophus]

Argentina testers (n = 6) report upload errors with yyyy/dd/mm and dd/mm/yyyy.
US (n = 2), New Zealand (n = 1) with mm/dd/yyyy formats do not.

[tdpearson]

This is also a locale and parsing issue. To address, the application should capture the user's locale preference and apply it when parsing the user supplied files. For Python 2.7: https://docs.python.org/2.7/library/locale.html