Product / Material Ontology Fix

[NicoWilh]

Problem
Currently not all classes have the same IRI in the .ttl file. This is causing issues in protege. Protege automatically creates new classes with wired IRI's (http://www.semanticweb.org/owl/owlapi/turtle#).

Solution options:

1. Change base prefix:
   

2. Add prod: prefix to all classes
   

[AlBaker]

Same issue appears in that file with SemiFinishedProduct. I'm going to fix both in a PR