make cli-config compatible with 2.4.x

1. composer now installs doctrine 2.4.x
2. vendor/bin/doctrine throws an error about $helperSet
3. apparently it wants the cli-config.php to return the $helperSet, see https://github.com/doctrine/doctrine2/commit/a7d764f6c07c6d7cb07fc4ccf7447e14a90ca569