Add locale option to translations task.
Updated base translation.
Allow the new 'Y' prefix for Spanish NIE numbers. Fixes #127.
Updated Argentina's ARCUITField to support legal types (24, 33) which are used in some special cases.

See Wikipedia for more details (spanish): http://es.wikipedia.org/wiki/Clave_%C3%9Anica_de_Identificaci%C3%B3n_Tributaria

Also added a test case for legal type 23.
Add BIC model and form fields.
Move country tuples into the generic.countries submodule.