go-tour: various updates for Go 1
go-tour: various updates for Go 1

R=golang-dev, adg
CC=golang-dev
http://codereview.appspot.com/5702045

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

karabinaa/go-tour-tr,karabinaa/go-tour-tr