The CI does not rebuild all generated files from source

[yanntm]

travis-ci currently does not regenerate all the classes i.e. replay the EMFgen part.

This means we have generated files in the git codebase which should not be the case, as we don't align correctly to new releases of the code generator and it makes issues like #10 a problem when they should be straightforward.

So, we should use the proper EMFgen/JET plugins for tycho/mvn that do exist now in standard places and use them to have a richer mvn scenario that actually rebuilds from manually edited artifacts only, and discard from source versioning the (literally hundreds) of generated files.