cargo_from_buck: get rid of signatures in generated Cargo.toml files
cargo_from_buck: get rid of signatures in generated Cargo.toml files

Summary: The signatures were used by the linter to warn if the files require regenerating, since the linter now regenerates the files regardless of the signature it is no longer needed to sign the files.

Reviewed By: krallin

Differential Revision: D20467745

fbshipit-source-id: aff2643f80939d5693e7a30abf07484c9060796f

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift