server: Add link to temperature graph

django/server/templates/server/index.html

@@ -45,7 +45,7 @@ requestbar-float {% if requestbar_collapsed != 'false' %}requestbar-collapsed{%
 		<div id="footer-lectures" class="col">
 			<span class="grey-text text-lighten-5" href="#!">Current Lecture:<span id="current_lectures">None</span></span>
 			<span class="grey-text text-lighten-2 hide-on-med-and-down" href="#!">Next Lecture:<span id="next_lectures">None</span></span>
-			<span class="grey-text text-lighten-5" href="#!">Temperature:<span id="current_temp">N/A</span></span>
+			<a target="_blank" href="https://wwwcip.informatik.uni-erlangen.de/temperature/day.png"><span class="grey-text text-lighten-5" href="#!">Temperature:<span id="current_temp">N/A</span></span></a>
 		</div>
 	</div>
 </footer>