Enable installing app as pwa

app/views/service_worker/service_worker.js

@@ -0,0 +1,14 @@
+function onInstall(event) {
+  console.log("[Serviceworker]", "Installing!", event);
+}
+
+function onActivate(event) {
+  console.log("[Serviceworker]", "Activating!", event);
+}
+
+function onFetch(event) {
+  console.log("[Serviceworker]", "Fetching!", event);
+}
+self.addEventListener("install", onInstall);
+self.addEventListener("activate", onActivate);
+self.addEventListener("fetch", onFetch);