removed JoinNode from the applyTransitiveEquivalence interface. Added comment not to forget to clone join tree before the transformation for >2 table outer joins
Merge remote-tracking branch 'alexeev/eng_3038' into ENG-3038
Merge branch 'master' into ENG-3038
Merge pull request #524 from VoltDB/ENG-3038

Eng 3038 post-review refactoring, no functionality change