C: add Jeremy Schlatter (Google CLA)

R=golang-dev, dsymonds
CC=golang-dev
https://codereview.appspot.com/7307070
io: Simplify CopyN implementation by delegating to Copy.

R=golang-dev, dave, minux.ma, bradfitz, rsc
CC=golang-dev
https://codereview.appspot.com/7312055

Committer: Brad Fitzpatrick <bradfitz@golang.org>