Convert to PSR-0

Fine day, chaps!

Non-namespaced code is so continental. Spiffing should adopt [PSR-0](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md) to allow for polite commingling amongst civilised projects.

This would, however, increase Spiffing's requirements to PHP 5.3 or greater. Terribly sorry about that.