Fix for "getpeerinfo" implementation

Clark,

I've put together a small patch that fixes the implementation of the "getpeerinfo" API call. The types were wrong in a couple of places, so parsing the JSON data would fail and you'd get a `BitcoinResultTypeError` every time.

Note that I'm using Bitcoin-Qt (v0.8.1-beta) rather than bitcoind. I assume the two clients share the same API, but I haven't been able to install bitcoind to confirm.

I've been playing around with information extracted from the blockchain, rather than creating transactions, so I might get into other parts of the API you haven't looked at closely. This is my first time using GitHub, but I'd like to get involved, so do let me know if you're looking for specific contributions.

Regards,

Eric