Allow to use new features from https://github.com/fzaninotto/Faker

This PR allow to use features implemented in:

https://github.com/fzaninotto/Faker/pull/105

(calling methods with formatter arguments in doctrine)

For example:
```yml
Entity\Something:
    custom_formatters:
        name: { method: words, parameters: [3, true] }
    custom_modifiers:
        setImage:
            - { method: randomElement, parameters: [ [some-dir/some-image.png] ] }
```

Will call method 'setImage' on entity 'Something' and will pass string generated by 'randomElement' formatter as 1st argument (you can use if you have some additional logic in setters or to call some other methods on entities...)