For ENG-4719, make the decision to delete a row during a scan specific to each predicate.
For ENG-4719, need to increment iterator
For ENG-4719, tackle doing the right thing with the delete predicate in the topend by including the info in the json
For ENG-4719, minor changes based on Ning's feedback
Merge pull request #533 from VoltDB/ENG-4719

Eng 4719 deleteTuples should be per output target, not per snapshot