Dead easy memoization of virgilio actions.
The goal of this extension is to make caching in virgilio very easy. It should only be a matter of providing an additional cache-timeout value to a defineAction call. From that point on, each response from that action is cached for that duration, keyed with a hash of the input arguments. In other words: calling the same action twice with the same arguments should only result in a single execution of the action itself.
Because this virgilio-extension extends one of virgilio's base functions, it is also a good testcase of virgilio's extension mechanism.