✨ (install PWA) Add install PWA app

src/App.vue

@@ -42,6 +42,7 @@
         @click="hideMenu"
       >
         <div class="navbar-end">
+          <install-app />
           <router-link
             class="navbar-item"
             :to="{ name: 'about' }"
@@ -73,13 +74,15 @@ import { Action, Getter } from 'vuex-class'
 import IUser from '@/models/IUser'
 import { COFFEE_LINK } from '@/utils/constants'
 import OnlineView from '@/components/OnlineView.vue'
+import InstallApp from './components/InstallApp.vue'
 
 @Component({
   directives: {
     ClickOutside
   },
   components: {
-    'online-view': OnlineView
+    'online-view': OnlineView,
+    'install-app': InstallApp
   }
 })
 export default class App extends Vue {