Unable to export orders if selected language is different from user language

[marfago]

When I try to export some orders, if the user default language is different from the chosen site language, the date in the the "to date" inputbox is not recognized and an error is issued. In particular, I've selected english but the user default language is italian: the date picker writes "12/31/2014" in the inputbox, but it is expected 31/12/2014. More, the language for the datepicker is german.