Merge pull request rustwasm#868 from alexcrichton/bump

Bump to 0.2.22

Bump to 0.2.21

Temporary fix for 0.2.20

Bump to 0.2.19

Bump to 0.2.18

At the same time, also add a `publish.rs` script to ease our publishing woes.

Bump to 0.2.17

futures: Add metadata to Cargo.toml

futures: Add metadata to Cargo.toml

Tweak travis config

guide: Also publish the test crates