Remove hop-by-hop headers.
Remove hop-by-hop headers.

We should have been doing this already for HTTP/1.1, but it didn't seem
to make problems. However, Safari has fits if it sees a Connection
header on an HTTP/2 response.

Change-Id: I5d289fb572b6d0bad7186a3cc340b64d39a25500

unixabg/redwood,andybalholm/redwood,unixabg/redwood,andybalholm/redwood