Serve old content if backed is slow.

[Anton Stonor]

Klaus wrote:

> I fact, the ideal way would be if content has expired, it would still 
> serve the old content until new content is retrieved from backend.

I believe "pre fetching" is on the drawing board and hopefully scheduled 
  for version 2.

It will probably make it possible to set up rules such as: Fetch a fresh 
copy from the backend 30 seconds before the object times out.

/Anton