Add sorted take optimizations
Address some review comments
Merge branch 'develop' into oscar-sortwithtake

Conflicts:
	scalding-core/src/main/scala/com/twitter/scalding/typed/KeyedList.scala
Style changes from scalariform
Step 1 on a bufferedTake monoid for unsorted cases
Move bufferedTake to KeyedListLike
Fix to avoid serializing the priority queue in the common case
Merge with develop
Actually exercise bufferedTake
Merge pull request #894 from twitter/oscar-sortwithtake

Add bufferedTake to do map-side takes