Converts the value into a DateTime object before setting.

def set(self, instance, value, **kw):
        """Converts the value into a DateTime object before setting.
        """
        if value:
            try:
                value = DateTime(value)
            except SyntaxError:
                logger.warn("Value '{}' is not a valid DateTime string"
                            .format(value))
                return False

        self._set(instance, value, **kw)