Jitter doesn't work with long page cache expirations

[KeithCu]

The jitter is a nice feature to spread out the requests slightly. That way when someone shows up, an hour after the server started, they will only have to fetch one request, as the other hourly requests will actually expire over the next 5 minutes.

However, it only works for short page cache lengths. Right now, with a page cache of 10 minutes, when that expires, the next user is often having to wait for multiple fetches. So either shorten the page cache to around 1 minute, or take out the jitter.

[KeithCu]

Changed the page cache to 5 minutes, and jitter to 15 minutes. That should hopefully split up the new requests between 3 separate pages. This of course assume people are showing up at least every 5 minutes.