Make the module autoloader to register class aliases for the classes that are migrated to namespaces, so that they are still accessible via the old name. This keeps everything working while migrating the classes.

Add a PSR-4 autoloader for modules. Now modules can declare their classes under the SimpleSAML\Module namespace.

This patch also starts using Composer for other dependencies
(i.e. php-openid and xmlseclibs).

Thanks to Boy Baukema for implementing this!

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@3290 44740490-163a-0410-bde0-09ae8108e29a