[DISCUSS] L14N Draft implementation for ResourceBundles (#14 continued)

This pull request is meant for discussion.

The implementation works, but I'm quite sure there is room for further improvement, esp. regarding m2e integration of the maven-plugin.

Also, the maven-plugin currently generates the ResourceBundles together with the java-classes (phase: `generate-sources`), but maybe this should move into a `generate-resources`

Added some tweaks suggested by @ansell