Rust implementation of the simple TDD task for Rhyme Harder

1. install Rust by following the instructions here: [http://doc.rust-lang.org/doc/tutorial.html#installation]
2. compile with rustc -g --test rhyme-harder.rs
3. run with ./rhyme-harder

If you're running windows, these steps will probably have to be modified slightly, by adding the odd .exe here and there perhaps.