carr/phone — pull request #27 by miloshadzic (2012-08-16 10:45:27+00:00)
Title: Add specific errors.

Some errors bubble up to surrounding code when phone is used. Hopefully this patch makes them easier to handle(it did for me).

Proposed exception structure in the patch:
```
RuntimeError
|-- PhoneError
|--NumberError
|--AreaCodeError
|--CountryCodeError
```

Please review.