Updating ALPN version.
Removing implementation draft notice, will restore after IETF Vancouver.
[#250] remove substitution from HPACK
Merge pull request #262 from jpinner/header_updates

[#250] remove substitution from HPACK
Renaming frame size error; using it consistently.  Fixes #246.
Merge branch 'master' of github.com:http2/http2-spec