add DateFormat for DateValidator

[Gerolf Seitz]

i was wondering if we could provide the facilities to set a
DateFormat/-Pattern (to format the date in feedback messages) for
DateValidators?
the default format in a feedback message via toString() (like "Sun Sep 23
23:59:55 CEST 2007") seems rather strange,
when the user needed to enter a date in a different format (which he
probably will).

i was thinking of the following:

add "DateValidator withDateFormat(DateFormat format)" and "DateValidator
withDatePattern(String pattern)" to DateValidator.
every DateValidator (Range, Minimum, Maximum) should add the variable values
like this:

protected Map variablesMap(IValidatable validatable)
        {
            final Map map = super.variablesMap(validatable);
            map.put("maximum", formatDate(maximum)); // use formatDate(Date)
            return map;
        }

the formatDate method either uses the provided dateformat to format the date
or otherwise (in case no dateformat/patter was provided) just returns the
result of the toString() method.

so, wdyt?

  gerolf