Supporting different build systems

At the 2014 hackathon we discussed how to support different build systems and reached agreement on some things. I've summarized those on this page:

1. When creating a new workspace, we allow you to select a single build system (Maven, Ant, Gradle, ...) from a list. The item you select can actually be a template for the whole cnf project.
2. Build systems should put their files in cnf//
3. New Project templates should honor the selected build system in the workspace and, if needed, only generate files for that build system.
4. We explicitly don't support having a workspace with different build systems per project.
5. Manually you could setup a workspace to use more than one build system (like Ant and Gradle).
6. We do not support switching build systems in an existing workspace. If you delete cnf and regenerate it, change the chosen build system, it will not magically adapt existing projects, so your build will break.