magento2 compatibility

[davidverholen]

As magento2 is coming fast now, we should try to have this helper lib abstract enough that it can also be used for custom magento2 Installers, as the current magento2 Installation seems pretty static and if they don't improve it very much at least I will need a custom Installer.

The mapping will be the same and the parsers basicially, too. As magento2 only uses the composer map setting, this should not be a Problem anymore.

The only change will be, that magento2 has different base paths for different Package Types. I think we should keep this in mind for this package.

Maybe we can have an additional configuration, implemented in the actual Installer, which defines different settings per package-type for the deployment.