Simplify DuSE-MT plugin controller implementation

Change-Id: Iecbd1b0893893268f82b998c1f0fcb6a13a8015d
Reviewed-by: Sandro S. Andrade <sandroandrade@kde.org>
Add association in example.xmi file

Change-Id: Ibfd50d3d1cfb2f758c3d30e2935f52332645e753
Reviewed-by: Sandro S. Andrade <sandroandrade@kde.org>
Improve UML concrete syntax DuSE-MT plugin implementation

Change-Id: I3952e437144a29eb0bdb333726f4076f22bf0b57
Reviewed-by: Sandro S. Andrade <sandroandrade@kde.org>