TLS handshake failures didn't use to log, but do in Go 1.3.
Shut it up so the actual failure can be seen in e.g.
http://build.golang.org/log/ede7e12362a941d93bf1fe21db9208a3e298029e

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/87870043