Add alternate language viewlet

Many websites serve users from around the world, with content that's translated, or targeted to users in a certain region. The rel="alternate" hreflang="x" annotations help Google serve the correct language or regional URL to searchers. Read more information about multi-regional and multilingual sites here: https://support.google.com/webmasters/answer/189077

This viewlet will render following code into your IHtmlHead viewlet manager:
```xml
    <link rel="alternate" hreflang="no-no" href="http://www.yourhostname.com/no/produkter" />
    <link rel="alternate" hreflang="nl-nl" href="http://www.yourhostname.com/nl-nl/producten" />
    <link rel="alternate" hreflang="sl-si" href="http://www.yourhostname.com/sl-si/izdelki" />
    <link rel="alternate" hreflang="da-dk" href="http://www.yourhostname.com/da-dk/produkter" />
    <link rel="alternate" hreflang="de-de" href="http://www.yourhostname.com/de-de/produkte" />
    <link rel="alternate" hreflang="ru-ru" href="http://www.yourhostname.com/ru/produkty" />
    <link rel="alternate" hreflang="cs-cz" href="http://www.yourhostname.com/cs-cz/produkty" />
    <link rel="alternate" hreflang="it-it" href="http://www.yourhostname.com/it-it/prodotti" />
    <link rel="alternate" hreflang="de-ch" href="http://www.yourhostname.com/de-ch/produkte" />
    ...
```