Refactor `Wot::Player` namespace and `Wot::Api` methods
- Refactor `Wot::Player::Info`.
- Refactor `Wot::Player::Statistics`.
- Removed useless files.
- `Wot::Error` class now extends `StandardError`.
- Now, instead of returning an `Wot::Error` object, `Wot::Api::make_request`
  will raise and `Wot::Error` exception.