integer value should be accepted when date-format is set to @ (timestamp)

[ulk200]

Hi, I had to set the datepicker with a timestamp value (integer), spefifying 'ui-date-format' to '@' but it was never parsed.

Line 92

  if (angular.isString(value) ) {
            return jQuery.datepicker.parseDate(dateFormat, value);
          }
          return null;
        });

Add an 'isNumber' test ? Or parse everything and catch all exception to return null ? Thanks.