fixed the acknowlegdement of river_items.
- targetOperation was missing test river tables.
- acknowlegdment is now processed after each bulk if the acknowlegde
setting is true.
The properties "source_timestamp", "source_operation" (rivertable) and
pseudocolums "ID","INDEX","TYPE" and "PARENT" are now not unnecessary
indexed as source properties.
riveritems with source_operation "delete" will now result in a delete in
ES.