Refactor ExecutorVector class.
Incorporate Paul's review comments.  Add back in smartpointer that was managing memory for PlanNodeFragment.
Merge branch 'master' into cwolff-refactor-executor-vector
Remove dead code, remove unneeded argument from ExecutorVector::init method
Merge branch 'master' into cwolff-refactor-executor-vector
Merge pull request #1731 from VoltDB/cwolff-refactor-executor-vector

Refactor ExecutorVector class