node-wot versioning

Let's move the discussion of #1028 about versioning here. We should also not forget https://github.com/eclipse-thingweb/node-wot/issues/462 and https://github.com/eclipse-thingweb/node-wot/issues/648

I think the main question is whether we want to have a 0.9.0 kind of release even if the scripting api does not change. I am open to bump that and to also consider a 1.0.0 release but that should be another discussion.