Transition fbcode Rust crates to 2018 edition
Transition fbcode Rust crates to 2018 edition

Summary: Marking all Cargo.tomls in fbcode as 2018 edition.

Reviewed By: jsgf

Differential Revision: D15951175

fbshipit-source-id: edf18449c214ee1ff285d6a2cb61839aaf58a8cd

nodakai/watchman,wez/watchman,nodakai/watchman,facebook/watchman,wez/watchman,facebook/watchman,wez/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,nodakai/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,facebook/watchman,nodakai/watchman,wez/watchman,wez/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,wez/watchman,facebook/watchman,wez/watchman,facebook/watchman