Adds QDB support and a cache for random quotes.

Hi. This patch adds support for qdb.us and caching of random quotes so fewer page fetches are required.

I had originally intended to upload a module to CPAN to support this (I wrote the code about a year ago : https://gist.github.com/jbarrett/5142315), but was wondering if it's better placed in WWW::BashOrg.

This patch should have no effect on existing code using your module.