Add static page de.serlo.org/beitrag

[Knorrke]

The page should have the following script loading a page of twingle. Apart from that we need the footer with impress and privacy policy as in de.serlo.org/spenden.

<!-- twingle -->
<script type="text/javascript">
    (function() {
        var u="https://spenden.twingle.de/embed/serlo-education-e-v/serlo-education-e-v/tw5cdc26358ab59/widget";
        var id = '_' + Math.random().toString(36).substr(2, 9);
        var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
        document.write('<div id="twingle-public-embed-' + id + '"></div>');
        g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'/'+id; s.parentNode.insertBefore(g,s);
    })();
</script>
<!-- twingle -->