View\Helper\Navigation\Menu: add flag to set page class to <li>

In ZF1 there was the possibility to put the page class to `<li>` instead of internal `<a>`:

https://github.com/zendframework/zf1/blob/release-1.12.3/library/Zend/View/Helper/Navigation/Menu.php#L103-L108

Before:
```html
<ul class="navigation">
    <li>
        <a class="foobar" href="site2">Site 2</a>
        <ul>
            <!-- [...] -->
        </ul>
    </li>
</ul>
```

After:
```html
<ul class="navigation">
    <li class="foobar">
        <a href="site2">Site 2</a>
        <ul>
            <!-- [...] -->
        </ul>
    </li>
</ul>
```

This behaviour is necessary to correctly style the internal `<ul>` of a specific `<a>` page.

Tests pass, I'll rebase when global test fail will be fixed.