Add es package

Looking for some feedback on this approach to talking to ES.
Perhaps use a template here? (see the text/template package)

e.g.

at global scope:

    var config = template.Must(template.New("").Parse(`
    path.data: {{.Dir}}/data
    path.logs: {{.Dir}}/log/
    network.host: 127.0.0.1
    http.port: {{.HttpPort}}
    `))

then in the function:

     config.Execute(file, es)