Replace broken link
Checkpoint the daily download state component after resetting

This avoids large eventlogs from building up for this state component.
Move the new package status to the bottom of the list on the page
Merge pull request #264 from fhartwig/bad-link

Replace broken link on /upload
Add header Vary: Accept when doing content negotiation
Be more parsimonious about what bits of happstack we import
Split and move the misc happstack utils module

Move it under the Framework heirarchy, and split out the ETag cache
feature into its own module.
Introduce a new cacheControl util, replacing useETag

In addition to an ETag, it emits the Cache-Control HTTP header.
In particular the useful controls are max-age, public and no-transform.
Use this in all the places where we had useETag, with sensible max-age
values.
Add cache control for static files and templates