Logo command doesn't work if a custom default command is set

For example:

```php
$app = new \Ahc\Cli\Application('Test App', '0.0.1');
$app->logo('My ASCII Art');
$app->command('cmd');
$app->defaultCommand('cmd');
```

```sh
# will not show the logo currently
./bin/my-app --help
```

Fixed by #112 