2to3 -f future . -w
This will remove imports from __future__ that are no longer needed. https://docs.python.org/3.5/library/2to3.html#2to3fixer-future
This basically commits the transpiled CoffeeScript JS (with minor cleanup) and removes coffee build support. A tiny amount of support for xblocks exists, because external users may have xblocks with coffee. But no coffee in our tree anyway.
