Filter_cache module released

Tested with up to nginx 1.0.6

Note: this currently doesn’t work when the ctx gets reset on named
locations. The quickest fix I have is to patch the request struct to
add a
filter_cache pointer.

Filter cache caches full responses after the results of filters such as
and gzip.

It was the first nginx module we ever wrote and it grew organically, so
code is krufty.