Ability to run `cargo test` with arguments - e.g. run only single test

[AndiDog]

In projects with many tests, you may only want to run a certain set of tests with cargo test mytestname mytest2. No idea how to implement this nicely, to be honest. My first idea was to read a file .atom-build-cargo.yml and then produce test targets for atom-build based on a user-provided list. Or use cargo test -- --list to get the actual list of tests (could be very many, though).

I could put that into .atom-build.yml myself but then would have to do all the error matching myself...