Replace cobertura with jacoco

Cobertura is not maintained for 2 years now and it has some errors. For example, if you look at [AsorOntology](https://universaal.github.io/ontology/ont.pom/cobertura/org.universAAL.ontology.asor.AsorOntology.html): it should be 100% covered, but it is only 90% (and some lines are count twice).

Has anyone experience with jacoco?
