Upgrade Rust.
Merge pull request #25 from servo/rustup-20140716

Upgrade Rust.
Generate documentation with rustdoc
Merge pull request #26 from servo/rustdoc

Generate documentation with rustdoc
Update to the last rust-nightly.

Version of rustc: 0.12.0-pre-nightly (01ec6fab2 2014-08-18 00:46:10 +0000).