Change codepool to community and adjust frontend location for compatibility

This includes the changes made in #19, rendering redundant if this is merged.

Magento extension development best practises are that an extension for community distribution should live in the `community` code pool.
This give local developers the ability to override parts of the extension without hacks.

For compatibility frontend should now live in `base/default` rather than `default/default`.

Quick reference for this is available on page 71 of [xCommerce's Magento Extension Developers Guide](http://info.magento.com/rs/magentocommerce/images/Magento-Extension-Developers-Guide-v1.0.pdf) from last year.