support creating projects from archetypes which don't use maven

we've a bunch of archetypes for projects like nodejs, golang, swift, python, ruby; we're also hoping to add archetypes for things like Gradle / SBT etc.

It'd be nice to allow the project-new wizard to not always create a pom.xml and src/main/* src/test/* folders if the archetype does not contain a pom.xml file.

PR on the way shortly...