Usage of Unit of Measure Ontology

[IKnowLogic]

Each Flow is currently (and correctly) making use of the Unit of Measure Ontology with a hasUnit relation to a measure. The object of these triples is however not correct. Currently the object is a URI to a units-of-measure resource, example (http://www.ontology-of-units-of-measure.org/resource/om-2/tonne), but we have already defined the measures we use in the named graph unit.ttl, which we should instead use.

[IKnowLogic]

Also the Unit of Measure Ontology has the concept hasNumericalValue. We instead rename the concept to hasNumericValue which is of cause shorter, but for the sake of consistency, and interoperability we should use the same name as them.