add composer.json and modman files

I've added a `composer.json` file and modman file for alternative means of distribution.

[Composer](http://getcomposer.org) is a dependancy manager for PHP used with the [Magento Composer installer](https://github.com/magento-hackathon/magento-composer-installer) it's a great way to manage dependancies.

[Modman](https://github.com/colinmollenhour/modman) is a popular script for Magento module deployment.

These two tools are ideal for users who manage their Magento project's through source control and not Magento Connect.

Also worth a look, because you're distributing though Connect, is [https://github.com/punkstar/modbuild](https://github.com/punkstar/modbuild).