[PATCH] support parameters for no-cache and private

Since we now support HTTP/1.1 storage and revalidation of
Cache-Control:no-cache it is important that we at least detect the cases
where no-cache= and private= contain parameters.

AFAIK these are still rare occurances due to the historic lack of
support. So for now Squid just detects and exempts these responses from
the caching performed. The basic framework for adding future support of
these HTTP/1.1 features is made available

Dmitry: Please run this past Co-Advisor to confirm the private="..." and
no-cache="..." cases are now all "Precondition Failed".

Amos