HTTP/2 Draft 16

Motivation:
HTTP/2 draft 16 has been released https://tools.ietf.org/html/draft-ietf-httpbis-http2-16.

Modifications:
The HTTP/2 codec should be updated to support draft 16.

Result:
HTTP/2 codec is draft 16 compliant.
I don't think so.  Just like all the other headers that are "excluded"...they are just ignored.  [section-8.1.2.2](https://tools.ietf.org/html/draft-ietf-httpbis-http2-16#section-8.1.2.2) doesn't mention throwing an error in this case.