Travis-cargo not working with Rust 1.10 and cargo 0.11

Ever since Rust 1.10 went stable, travis-cargo doesn't update test coverage anymore on coveralls (no new builds are being recognized). Temporary workaround is to add a 1.9.0 target in .travis.yml which fixes the problem but it would be great if it could work out of the box with latest stable release. :)
