Removed PSR-0 statement

Since Piwik does NOT follow PSR-0, composer makes unnecessary file system calls for every single class. Piwik's own autoloader knows how to load Piwik's classes.
Merge pull request #102 from SgtK/master

Removed PSR-0 statement since it's not valid at this stage (see dicussion in http://dev.piwik.org/trac/ticket/4074#comment:2 for next steps)