Add i18n for index.html

aleksis/apps/mensa/templates/mensa/index.html

 {% extends "core/base.html" %}
-{% load msg_box static %}
+{% load msg_box static i18n %}
 
 {% block content %}
   <a class="waves-effect waves-light btn green" href="{% url "menu_upload" %}"><i class="material-icons left">add</i>
-    Neuen Speiseplan hochladen
+    {% trans "Upload new menu" %}
   </a>
   <a class="waves-effect waves-light btn orange" href="{% url "menu_show_current" %}"><i class="material-icons left">picture_as_pdf</i>
-    Aktuellen Speiseplan anzeigen
+    {% trans "Show current menu" %}
   </a>
 
-  <h5>Übersicht der hochgeladenen Speisepläne</h5>
+  <h5>{% trans "All uploaded menus" %}</h5>
 
   <ul class="collection">
     {% for menu in menus %}
@@ -17,10 +17,10 @@
         <span class="title">{{ menu }}</span>
         <p>
           <a class="btn-flat waves-effect waves-green" href="{% get_media_prefix %}{{ menu.pdf }}" target="_blank">
-            <i class="material-icons left">picture_as_pdf</i> Anzeigen
+            <i class="material-icons left">picture_as_pdf</i> {% trans "Show" %}
           </a>
           <a class="btn-flat delete-menu waves-effect waves-red" href="{% url "menu_delete"  menu.id %}">
-            <i class="material-icons left">delete</i> Löschen
+            <i class="material-icons left">delete</i> {% trans "Delete" %}
           </a>
         </p>
       </li>