Rename 'make build' to 'make docker-image' so it's more obvious what it's doing
Initialize git submodules automatically when needed, so users don't need to do it manually
Go 1.8 introduced checking of script type and templates are no longer loading, as the script type is not allowed by Go 1.8
https://github.com/golang/go/issues/18569 captures the details.
Change template script type to one of the allowed types, it doesn't matter for clientside-haml-js, it only needs to match the script id
