Global install + running in a vendor subdir

My situation:
  * I installed PhpSpec globally (`composer global require phpspec/phpspec`).
  * I have a project that I want to write specs for. This contains all the domain-specific classes, but not the HTTP layer. Therefore I have my classes under test in the vendor/A/B/ directory (which is where I want to run phpspec), with all the dependencies available through vendor/autoload.php.

This means when running phpspec globally, it should check for an autoload.php file two levels up, too. Just as it does for local installs. Which is what I did here. =)