Added WPPM_Contributor->homepage, code to default it in the __construct() method, and a fixed up to support an ROOT->author_homepage so we can support the semantics of this format http://1.shadowcdn.com/files/external-update-example/info.json from http://w-shadow.com/blog/2010/09/02/automatic-updates-for-any-plugin/.
- Renamed WPPM_Package->$bundledDependencies to bundled_dependencies and allowed bundled_dependencies to default to all dependencies if not set.
- Dropped WPPM_Package->wordpress object and added requires and tested properties instead.
Captured unused JSON properties into a WPPM_Container->unused property instead of throwing a warning so that _fixup() methods can access them (I might later add a warning message after all fixups have been run.)