resolves #23: In-browser notification

This implements web notifications on job completion. Opt-in
by default, the preference is saved in js localStorage and
can be toggled directly on any page

src/resources/index.html

@@ -25,6 +25,9 @@
   a.navbar-btn.active { color: #fff; }
   a.navbar-btn:hover { color: #fff; text-decoration: none; }
   a.navbar-btn:focus { color: #fff; }
+  .bell { margin: 8px 15px; color: #9d9d9d; }
+  .bell:hover { text-decoration: none; color: #9d9d9d; cursor: pointer; }
+  .bell.active { color: #333; }
   dt,dd { line-height: 2; }
   canvas {
    width: 100% !important;
@@ -219,13 +222,12 @@
 
  <div id="app">
   <nav class="navbar navbar-inverse">
-   <div class="container-fluid">
    <div>
     <router-link to="/" class="navbar-brand"><img src="/icon.png">{{title}}</router-link>
     <router-link to="/jobs" class="btn navbar-btn pull-right">Jobs</router-link>
    </div>
-   </div>
   </nav>
+  <a v-on:click="toggleNotifications(!notify)" v-show="supportsNotifications" class="bell pull-right" :class="{'active':notify}" :title="(notify?'Disable':'Enable')+' notifications'">&#128276;</a>
   <router-view></router-view>
   <div v-show="!connected" id="popup-connecting"><img src="/spin.gif">&nbsp;Connecting...</div>
  </div>

src/resources/js/app.js

@@ -32,9 +32,12 @@ const WebsocketHandler = function() {
         // at this point, the component must be defined
         if (!this.comp)
           return console.error("Page component was undefined");
-        else if (typeof this.comp[msg.type] === 'function')
+        else {
+          this.comp.$root.showNotify(msg.type, msg.data);
+          if(typeof this.comp[msg.type] === 'function')
             this.comp[msg.type](msg.data);
         }
+      }
     };
     ws.onclose = function(ev) {
       // if this.comp isn't set, this connection has never been used
@@ -513,7 +516,28 @@ new Vue({
   el: '#app',
   data: {
     title: '', // populated by status ws message
-    connected: false
+    connected: false,
+    notify: 'localStorage' in window && localStorage.getItem('showNotifications') == 1
+  },
+  computed: {
+    supportsNotifications() {
+      return 'Notification' in window && Notification.permission !== 'denied';
+    }
+  },
+  methods: {
+    toggleNotifications(en) {
+      if(Notification.permission !== 'granted')
+        Notification.requestPermission(p => this.notify = (p === 'granted'))
+      else
+        this.notify = en;
+    },
+    showNotify(msg, data) {
+      if(this.notify && msg === 'job_completed')
+        new Notification(data.name + ' ' + '#' + data.number +' completed');
+    }
+  },
+  watch: {
+    notify(e) { localStorage.setItem('showNotifications', e ? 1 : 0); }
   },
   router: new VueRouter({
     mode: 'history',