`artisan dump-autoload` should handle the actual dumpAutoload, and only call optimize when app.debug === false

This is a new pull request based on the discussions with other developers in issue #1303. This will make it so the `compiled.php` file is not generated when `app.debug === true`. This helps with debugging and local development as it cuts out the time hunting down the file in which an error occurred as we don't have to muck with the `compiled.php`.