Exclude Tests directory on composer archive

Hi,

I got troubles when attempted to install the bundle with `composer install --dev --prefer-dist`.

When archiving sources, it throw this exception due to the cyrilic characters:

```shell
[BadMethodCallException]
  Entry Tests/Fixtures/assets/АГГЗ.jpeg cannot be created: phar error: invalid path "Tests/Fixtures/assets/АГГЗ.jpeg" contains illegal character
```

To solve it, I [excluded the tests directory](http://getcomposer.org/doc/04-schema.md#archive) on archive creation:

```json
"archive": {
    "exclude": ["/Tests"]
},
```

Thanks.