CONTRIBUTORS: add Matthew Dempsky (Google CLA)

R=golang-dev, agl
CC=golang-dev
https://codereview.appspot.com/7049043
net/http: Sync TimeoutHandler godoc with code.

TimeoutHandler was changed from "ns int64" to "dt time.Duration" on
Nov 30, 2011, but the godoc still refers to "ns".

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/7031050

Committer: Ian Lance Taylor <iant@golang.org>