Correct the Flattr URL.

lib/components/App.js

@@ -57,7 +57,7 @@ export default class App extends React.Component {
         </div>
         <footer className="footer">
           <p>
-            <script id="fb13c4g" dangerouslySetInnerHTML={{__html: "(function(i){var f,s=document.getElementById(i);f=document.createElement('iframe');f.src='//api.flattr.com/button/view/?uid=kern&button=compact&url='+encodeURIComponent(document.URL);f.title='Flattr';f.height=20;f.width=110;f.style.borderWidth=0;s.parentNode.insertBefore(f,s);})('fb13c4g');"}} /> Donations: <strong>1P7yFQAC3EmpvsB7K9s6bKPvXEP1LPoQnY</strong>
+            <script id="fb13c4g" dangerouslySetInnerHTML={{__html: "(function(i){var f,s=document.getElementById(i);f=document.createElement('iframe');f.src='//api.flattr.com/button/view/?uid=kern&button=compact&url=http%3A%2F%2Fgithub.com%2Fkern%2Ffilepizza';f.title='Flattr';f.height=20;f.width=110;f.style.borderWidth=0;s.parentNode.insertBefore(f,s);})('fb13c4g');"}} /> Donations: <strong>1P7yFQAC3EmpvsB7K9s6bKPvXEP1LPoQnY</strong>
           </p>
 
           <p className="byline">