* Make request.Request smaller

This makes the request struct smaller and removes the pointer to the do
boolean (tri-bool) as size == 0 will indicate if we have cached it.

Family can be a int8 because it only carries 3 values, Size itself is
just a uint16 under the covers.

This is a more comprehensive fix than #3292

Closes #3292
Signed-off-by: Miek Gieben <miek@miek.nl>

* cache: fix test

this now needs a valid response writter
Signed-off-by: Miek Gieben <miek@miek.nl>