Improved array support for "data" attribute in renderTagAttributes()

I suggest to add more advanced support to render nested arrays in "data" attribute of tag (HTML5).

Here is example: 
http://api.jquery.com/data/#data-html5

This: 
```php
echo Html::tag('div', '', [
    'data' => [
        'role' => 'page',
        'last-value' => 43,
        'options' => [ // nested array
            'name' => 'John',
        ],
    ],
]);
```
will be rendered as: 

```html
<div data-role="page" data-last-value="43" data-options='{"name":"John"}'></div>
```