Adding BaseConfiguration class providing a set of magic methods to accesses setters and getters as properties.

Adding BaseConfiguration class providing a set of magic methods to access setters and getters as properties.

Useful e.g. in Yii2 framework as it allows to instantiate configuration as an application component. For example:
```php
'ApaiIOConfig' => [
            'class' => 'ApaiIO\Configuration\GenericConfiguration',
            'accessKey' => 'your_access_key',
            'secretKey' => 'your_secret_key',
            'associateTag' => 'your_associate_tag',
            'country' => 'co.uk'
        ],
```

You can also access getters as properties in Yii this way, e.g.
```php
$tag = Yii::$app->ApaiIOConfig->associateTag;
```
Also removed unnecessary  use statement from GenericConfiguration as Country class is located in the same namespace