Include all changes made during the extraction of DBpedia 2014

This PR includes all changes and bug fixes that were made during the extraction run of DBpedia 2014.

This includes:
 *  Additional ontology metadata
 *  Writing of property hierarchies to the ontology
 *  Fixed constant mappings
 *  First version of anchor text and surface form extraction code
 *  Additional namespaces
 *  Some utility classes