rust-shed/futures_01_ext: rename futures_ext to futures_01_ext
rust-shed/futures_01_ext: rename futures_ext to futures_01_ext

Summary: As part of the effort to deprecate futures 0.1 in favor of 0.3 I want to create a new futures_ext crate that will contain some of the extensions that are applicable from the futures_01_ext. But first I need to reclame this crate name by renaming the old futures_ext crate. This will also make it easier to track which parts of codebase still use the old futures.

Reviewed By: farnz

Differential Revision: D24725776

fbshipit-source-id: 3574d2a0790f8212f6fad4106655cd41836ff74d

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