It's already in old/template; make that build.
Update a couple of references to point to the old template.
They can be updated later.
Update goplay to use exp/template.
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4902046
First step of moving exp/template into template: save the old code.
Code is unedited except for target name in Makefile.
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4893042