Primitive auto reload for monitoring pane

reload the monitoring page every 30 secondsa
checkbox to enable/disable auto refresh

screenshot:
https://imagebin.ca/v/3UAtqA25IGK5

longer term, we want a more refined implementation with
refreshing partial page and customizable refresh interval.
But this primitive solution works reasonably well to start.

Implements blueprint enhance-congress-dashboard
Partial-Bug:#1670520

Change-Id: I50b678682480d5f2686fb099a6093ac9eb60aa52

congress_dashboard/monitoring/templates/monitoring/index.html

@@ -8,6 +8,26 @@
 
 {% block main %}
   <div id="monitoring_panel">
+    <script type="text/javascript">
+    // primitive auto-reload every 30 seconds
+    function makeReloadInterval() {
+      return setInterval(function(){location.reload();}, 30000);
+    }
+    reloadInterval = makeReloadInterval()
+    function toggleRefresh() {
+      checkbox = document.getElementById("checkBox_auto_refresh")
+      if (!checkbox.checked) {
+        clearInterval(reloadInterval)
+      }
+      else {
+        reloadInterval = makeReloadInterval()
+      }
+    }
+    </script>
+    <input id="checkBox_auto_refresh" type="checkbox" checked onclick="toggleRefresh()">
+    <label for="checkBox_auto_refresh">
+      Auto refresh (every 30 seconds)
+    </label>
     {{ monitoring_table.render }}
   </div>
   <script type="text/javascript">