rust-shed: unify Cargo.toml definitions
rust-shed: unify Cargo.toml definitions

Reviewed By: farnz

Differential Revision: D18726052

fbshipit-source-id: 4f18430342ab6fd4fc82cc7d03e21f3e50e0ce25

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