Bug 2287: Send a 505 on requests with unsupported HTTP versions

Squid currenty accepts requests with well-formed 0.9, 1.0, and 1.1 versions
and one special case of mising version (assumed to be 0.9 legacy requests)

All others including well-formed 0.x < 0.9 are now aborted with a
HTTP 1.1 compliant 505 Version Not Supported error.

diff --cc src/client_side.cc
Simple merge

diff --cc src/client_side_reply.cc
Simple merge