Time manipulation is not supported for cookie expiry

[jeroenvandijk]

The Expires cookie attribute is supported, but in order to test cookie expiration we need to actually wait for the expiry to happen. This becomes quickly infeasible if the expiry is minutes, hours or even days away. We would have to use (Thread/sleep (* 60 1000)) ... etc to do this somewhat reliably.

My proposal is to add an extension point to override the current time instead of relying on the current system time (i.e. (Date.)). An example of something like this can be found in Manifold