Simplify stereotype matching
Implement copyXXX() utility methods for scope and stereotype
Copy artifact stereotype to JPP artifacts

JPP artifacts need to have stereotype because repository stereotype
matching is done on JPP artifacts.
Don't try to visit non-class files

Objectweb ASM throws IllegalArgumentException when trying to read
non-class file.  Checking file magic might be a better idea, but
filtering files by extension should work too.
[test] Add test case for native code detection