update for rust 0.12.0-pre (or 0.11)

`println` was changed in Rust a while back to the `println!()` macro, which is now reflected in the code.

All Rust code, excluding your `chain_of_responsibility.rs` (unimplemented) now compiles on Rust

    rustc 0.12.0-pre

commit

    e178ebf681d532c1c965883ae34788713f748960

The `iPhone` -> `IPhone` change might be controversial - it's now linted by the Rust compiler (so the old code throws a warning), and while these can be hidden, the current [naming conventions guidelines](http://aturon.github.io/style/naming.html) suggest camelcase structs ...

Also, this should compile with `rustc 0.11` just as easily as with the nightlies. It's not exactly a major change.