io/ioutil: close file in TestWriteFile before deleting it
io/ioutil: close file in TestWriteFile before deleting it

R=golang-dev, dsymonds
CC=golang-dev
http://codereview.appspot.com/5495086
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go