Show message if there are no events

Closes #7 (closed)

version 1

version 2 after suggestions from @hansegucker

aleksis/apps/dashboardfeeds/templates/dashboardfeeds/ical.html

@@ -7,11 +7,15 @@
       <div class="card-panel event-card">
         <span class="title">{{ event.name }}</span><br>{{ event.date_formatted }}
       </div>
+    {% empty %}
+      <span>{% trans "No events to display" %}</span>
     {% endfor %}
   </div>
+  {% if feed_events %}
   <div class="card-action">
     <a href="{{ base_url }}" target="_blank">
       {% trans "Further events" %}
     </a>
   </div>
+  {% endif %}
 </div>