Author: Alex Rousskov <rousskov@measurement-factory.com>

Author: Alex Rousskov <rousskov@measurement-factory.com>
HTTP/1.1: respond to OPTIONS requests with a zero Max-Forwards value.

RFC 2616 section 9.2 says that a proxy MUST NOT forward requests with a
zero Max-Forwards value. RFC 2616 does not define any proper OPTIONS
responses, so we consider successful responses optional and reply with
501 Not Implemented.

No change in handling OPTIONS requests with positive Max-Forwards values.

While TRACE and OPTIONS are similar with regard to Max-Forwards, we
handle them in different places because OPTIONS responses do not need to
echo the request via Store.

Co-Advisor test case: test_case/rfc2616/maxForwardsZero-OPTIONS-absolute