Lookahead Ontology ID before parsing the content stream, and decide on proceeding accordingly

Currently, Stanbol does not try to guess the ID of an ontology until it has already loaded it (and presumedly stored it into Clerezza).

However, if we could obtain the OntologyID (comprehensive of versionIRI as well) prior to storing the graph, it would be possible to implement policies such as refusing to store an ontology whose ID matches the one of a stored ontology.

The ClerezzaOWLUtils method to guess the ID has an initial implementation, but it must be extended to support versionIRI and put into production.