This is a large commit.
The rfc7230 test suite adds many tests from the RFC7230 document.
Gun has been updated quite a bit recently, which broke the Cowboy
suites. This is now fixed with this commit.
A new hook onfirstrequest has been added. It was very useful during
debugging of the test suites.
The initial process code has changed a little; more changes are
expected with the switch to maps for options.
This document lists all rules that Cowboy HTTP server will follow
after careful analysis of the RFC7230.
Do note that not all these rules are implemented or tested yet,
and that at the time of commit there may be rules that Cowboy will
ultimately not implement (for various reasons including performance
or leaving certain aspects up to the user code).
