http2: remove h2-14 ALPN proto

"h2-14" was draft 14 of http2. It's past time to retire announcing it.
Everybody has been using "h2" in the wild for quite some time now.

The Google GFE doesn't accept it anymore either.

Change-Id: I087681a0a5e7117de3ab74a2f3f9e0ae45e007cd
Reviewed-on: https://go-review.googlesource.com/32576
Reviewed-by: Tom Bergan <tombergan@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2 files changed