Allow $GOVERSION to override anything set in the json files
Allow $GOVERSION to override anything set in the json files

michael-go/heroku-buildpack-go,michael-go/heroku-buildpack-go,titanous/heroku-buildpack-go,heroku/heroku-buildpack-go,cloudfoundry/go-buildpack,cloudfoundry/go-buildpack,heroku/heroku-buildpack-go,cloudfoundry/go-buildpack