If you can't go PHP > 5.4 then open app/lib/integrity-check.php and get rid of the PHP restriction. Just remove these lines:
PHP:
if(version_compare(PHP_VERSION, '5.5.0', '<'))
$install_errors[] = 'This server is currently running PHP version '.PHP_VERSION.' and Chevereto needs at least PHP 5.5.0 to run. You need to update PHP in this server.';