Add saref:Device as subclass of saref:FeatureOfInterest and s4syst:System.

In the new version, saref:Device is explicitly a subclass of saref:FeatureOfInterest and s4syst:System. In s4inma core:Device is used and extended with s4inma:ProductionEqupiment.

The proposal is to reuse the core superclasses of saref:Device.