A standalone script to setup sgw/couchbase

At the moment there isn't a quick way to setup SGW/Couchbase. This would be useful for various things, such as debugging, reproducing things and doc writing.

• A Docker-based script is a possibility, although I'm not sure that we have a Docker image for every build.
• It's also worth making sure that there isn't already something that does it (except for the framework, that does it, but requires setting up).