Missing dependencies when creating custom Faker Providers

Hi there!

Maybe I am missing something but following README instruction for adding new Faker providers lead me to the following error:

Symfony\Component\Debug\Exception\ContextErrorException]
Catchable Fatal Error: Argument 1 passed to Faker\Provider\Base::__construct() must be an instance of Faker\Generator, none given...

Every Faker Provider needs the dependency @faker.generator however this service is not registered by the bundle so if I add it the way:

``` yaml
services:
your.faker.provider:
class: YourProviderClass
arguments: [@faker.generator]
tags:
- { name: h4cc_alice_fixtures.provider }
```

I get the non existing dependency error.

Any clue?