Notification system enhanced

- Base for notifcation center
- Show text in map if no data is available

frontend/src/app/app.module.ts

@@ -20,6 +20,7 @@ import { environment } from '../environments/environment';
 import { AdminComponent } from './admin/admin.component';
 import { AlertComponent } from './_alert/alert/alert.component';
 import { FontAwesomeModule } from '@fortawesome/angular-fontawesome';
+import { NotificationsComponent } from './notifications/notifications.component';
 
 @NgModule({
   declarations: [
@@ -31,7 +32,8 @@ import { FontAwesomeModule } from '@fortawesome/angular-fontawesome';
     UserComponent,
     DashboardWidgetComponent,
     AdminComponent,
-    AlertComponent
+    AlertComponent,
+    NotificationsComponent
   ],
   imports: [
     BrowserModule,