Fix for timezone-related bug in validation plugin's "additional" method dateITA.

The "additional" validation method dateITA mixed local and UTC date functions, leading to incorrect validation for some dates.

Found this during testing in the GlobalBake/Farmlands project, when it reported 31/3/2015 as an invalid date. Examined the code and spotted the flaw.

This small fix for v0.13.0 or 0.13.1 is the same one that they used to fix the problem in their later release 0.14.0

https://github.com/jzaefferer/jquery-validation/releases/tag/1.14.0

https://github.com/jzaefferer/jquery-validation/blob/master/changelog.md#additionals