Updated the xdebug.scream

Ive been getting a PHPParser class issue recently and setting the xdebug.scream=1 to 0 seemed to have worked, for me. view issue post here http://laravel.io/forum/04-17-2014-undefined-variable-undefinedvariable-in-composer-install?page=1#reply-5314  and https://github.com/nikic/PHP-Parser/issues/89


This is only probably applicable if installing laravel and/or PHPparser.