Node to Row objects
- removed peerDeparture in solr remote search in case that peer does not
answer (this may be normal because it is allowed to switch this off)
solr as fulltext search index.
- added slow migration from old metadata to solr index entries: each
entry from the old metadata is removed from that data structure and
written into solr.
to have a fall-back option in case that memory problems as reported in
http://forum.yacy-websuche.de/viewtopic.php?p=26901#p26901
for full-solr installation are too strong and we have to work with an
'small memory footprint' peer system.