Skip TextAnnotations without EntityAnnotations

[fago]

Stanbol's NamedEntityRecogniztion often generates annotations with an existing entity. That creates troubles as those annotations get linked to http://stanbol.apache.org/ontology/entityhub/query#QueryResultSet. As this URI is not a proper entity in stanbol either, more errors occurs once the annoatted text is annotated another time.

Maybe best we could just skip annotations with an EntityAnnotation for now? (Suggest adding a new entry would be a nice feature addition afterwards)