message: App: Disable old avatar <img>
diff: <span *ngIf="isLoggedIn()">
  <button mat-button routerLink="/profile">
  - <img class="avatar" src="{{userService.user.getUserImageURL(30)}}" width="30" height="30"> <!-- FIXME remove/replace -->
  + <!-- <img class="avatar" src="{{userService.user.getUserImageURL(30)}}" width="30" height="30"> --> <!-- FIXME remove/replace -->
  <span class="avatar" [user-image]="userService.user" [size]="'30px'"></span>
  <span class="firstname-wrapper">{{ this.userService.user.profile.firstName }}</span>
  </button>
  