First attempt at switching to RustcEncodable and RustcDecodable

I need help on making this actually work; it `make && make test`s well;
however, after serving, the module for rustc_serialize doesn't exist. I do not
know how to get around it, or even if we want to; we need to do something,
though, because `Decodable` and `Encodable` are now deprecated, and
rustc-serialize is an external crate.