Go: Update to go 1.2rc2

Update from go 1.2rc1 -> 1.2rc2

Change the test to run `go fmt` vs `go vet` as in 1.2 `go vet` is in the go.tools subrepo for go in 1.2 and beyond.

The instructions for devel point out this change and a link to the go documentation citing [this](http://tip.golang.org/doc/go1.2#go_tools_godoc)