Remove vendor/ from PSR-0 examples

This has come up in conversation a few times, where some users were making a direct connection between Composer and PSR-0 due to having the "vendor/" directory in there.

This to me is a trivial change, which might help reduce some confusion. They think that EVERYTHING inside the vendor/ folder should be PSR-0, which if you're using Composer it wont be, as Composer vendor-name/package-name is not PSR-0 compatible nor is there any requirement for packages the selves to contain any PSR code at all.

Vote here: https://groups.google.com/forum/?fromgroups=#!topic/php-fig/VWpowatynOQ