Possible Cargo org

[nrc]

Should we create a GitHub org for Cargo (or for both Cargo and crates.io)? It would be home to crates which are used by Cargo or by Cargo plugins or for Cargo plugins themselves which are maintained by the Cargo team.

We discussed this at today's Cargo meeting and the response was not wildly enthusiastic, so we will add crates to the Cargo repo and use the rust-lang org for now, and if that doesn't work out so well, then we try a new org.