Public API for ontology key management

It has been reported that the public keys generated by the Clerezza implementation for storing ontologies is not always intuitive, especially when an ontology is anonymous.

Moreover, it is sometimes desirable to provide a simpler public key than the ontologyID anyhow (e.g. "foaf" instead of, or along with, "http://xmlns.org/foaf/0.1/").

Since aliasing is already implemented internally, it could be useful to have it manageable by the clients via a Java and RESTful API.