apply pyfmt with usort to opted-in sources
apply pyfmt with usort to opted-in sources

Reviewed By: zertosh

Differential Revision: D24880203

fbshipit-source-id: 2034cdfc2712209e86d3d05c119c58f979b05c52

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly