Update copyright in footer

schoolapps/templates/partials/footer.html

 <footer class="page-footer primary-color">
     <div class="footer-copyright">
         <div class="container">
-            © 2017 Computer-AG, Katharineum zu Lübeck
+            © 2018 Computer-AG, Katharineum zu Lübeck
             <a class="grey-text text-lighten-4 right" href="">Impressum</a>
         </div>
     </div>
 </footer>
 </body>
-</html>
\ No newline at end of file
+</html>