Fix autload check: phpunit has the script at the root directory, which means the search path is wrong when copying it into bin/

This fixes the following annoying error when using phpunit-randomizer in
a project through composer:

You need to set up the project dependencies using the following commands:
wget http://getcomposer.org/composer.phar
php composer.phar install
Merge pull request #7 from CodeYellowBV/master

Fix autload check: phpunit has the script at the root directory