Move Dependants common code to graph
Move to sbt 0.13, sbt-gitflow wasn't compatible. Not in this… needed?
Merge pull request #322 from twitter/feature/sbt-0.13

Move to sbt 0.13, sbt-gitflow wasn't compatible. Not in this… needed?
Merge pull request #321 from twitter/dependant-gen

Move Dependants common code to graph
Merge branch 'develop' into transOutput

Conflicts:
	summingbird-core/src/main/scala/com/twitter/summingbird/Dependants.scala
FlatMapKeys optimization in scalding