expiration-date 1.1.0

Really simple caching by attaching an expiration date to attributes. The ExpirationDate module adss two methods to a class -- expiring_attr and expiring_class_attr. These two methods are used to declare attributes in the instance and in the class, respectively, that will expire after some period of seconds have elapsed. The attribute is re-initialized from the given block after it has expired. This is a very simple form of caching.