[WIP] Atoum command

Work in progress implementation of atoum command. (discussion begin here #9)

```shell
$ app/console atoum FooBundle # FooBundle
$ app/console atoum FooBundle bar ...... #FooBundle and bundle which has `bar` as bundle alias extension.
$ app/console atoum # all bundles configured on config_test.yml
```

`config_test.yml`
```yml
atoum:
    bundles: [FooBundle, BarBundle]
```