Fix problem with prov_hasSources not being indexed
Add check in iindex unit test for 'prov_hasDerivations' field
Merge the code for rdfxml subprocessor from d1_cn_index_processor to metacat.
Add the prefix "prov_" the solr fields.
Use a new class to overwrite the class RdfXmlSubprocessor in d1-processor since that one has a method to use solr http server directly.