Expand normalizeUserAttributeMap

I have refactor method `normalizeUserAttributes` to expand for `normalizeUserAttributeMap` and add example for config client.
Please review. If you think that is reasonable please merge it and complete docs for it.

Thanks
Syntax becomes too heavy: there is no need for 'normalizedName' and 'actualName' keys.
It can be simplier:
```php
['about_me' => 'bio'],
['birthday' => function($actualValue) {...}],
```