Add prefix/suffix handling in PropertyMapping

This pull request (which is a minor extension of @ninniuz's code from dbpedia#41) adds prefixes and suffixes support to PropertyMapping for both DatatypeProperty and ObjectProperty. This adds three new parameters to {{PropertyMapping}} as documented at http://mappings.dbpedia.org/index.php/Template:PropertyMapping. It closes gaurav#29, dbpedia#20 and dbpedia#41.

This pull request also includes an updated ontology and Mappings to test this new code.