Dispatch events to service worker object and refactor html tests

tests/html/service-worker/sw_dashboard.js

@@ -1,2 +1,9 @@
-importScripts('dummy.js');
-console.log("dashboard service worker: active");
+importScripts('dashboard_helper.js');
+
+self.addEventListener('activate', function(e) {
+	status_from_dashboard();
+});
+
+self.addEventListener('fetch', function(e) {
+	console.log("A fetch event detected by /dashboard service worker");
+});