add possibility to dump all bundle configurations in ConfigDumpReference

In PhpStorm Symfony2 plugin we now have the possible to autocomplete config / security keys. It uses the xml output of `config:dump-reference`. plugin includes a default dump on standard edition, but per project dump is possible `/idea/symfony2-config.xml`.

Currently there so no way to dump all configs. would be nice if everyone can create it on a single command:

```php
php bin/console config:dump-reference * --format=xml
```

corresponding foreign file
https://github.com/Haehnchen/idea-php-symfony2-plugin/blob/master/src/resources/symfony2-config.xml

![phpstorm-symfony2-plugin](https://cloud.githubusercontent.com/assets/1011712/3076794/aa639a9a-e3fd-11e3-8b8e-26e8691fd2fc.png)


I don't like this logic in the command. Imo, the command should only have logic about how to execute the dumper, not about what the dumper is dumping.

Furthermore, this is invalid. It should dump:
````xml
<container xmlns="http://symfony.com/schema/dic/services">
````