solved "Fatal error: Call to undefined method PHPUnit_Util_Filter::addDirectoryToFilter()" that happens if PHPUnit version 3.5 or newer is used

Method PHPUnit_Util_Filter::addDirectoryToFilter() was removed in PHPUnit 3.5 (https://github.com/sebastianbergmann/phpunit/commit/150341273801b55392d0bde99fc7be60f5a5c15d).