title: Angular2-Meteor *ngIf with Meteor.userId() not updating reactively
body: <p>I am still pretty new to angular2-meteor and am trying a simple custom login buttons component.  I want to display Sign Up and Log In buttons when there is no user logged in and display the Log Out button when a user is logged in.  It seemed like it ought to be pretty simple, but it doesn't work as I am expecting.</p>
  
  <p>Here is my component html:</p>
  
  <pre><code>&lt;div *ngIf="!isLoggedIn()"&gt;
      &lt;button class="btn btn-outline-primary btn-sm" (click)="goToLoginForm()"&gt;Log In&lt;/button&gt;
      &lt;button class="btn btn-success btn-sm"&gt;Sign Up&lt;/button&gt;
  &lt;/div&gt;
  
  &lt;div *ngIf="isLoggedIn()"&gt;
      &lt;button class="btn btn-outline-danger btn-sm" (click)="logout()"&gt;Log Out&lt;/button&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>And here is my typescript:</p>
  
  <pre><code>import {Component} from "@angular/core";
  import template from "./login-buttons.component.html";
  import {Router} from "@angular/router";
  
  @Component({
      selector: "login-buttons",
      template
  })
  export class LoginButtonsComponent {
  
      constructor(private router: Router) {}
  
      isLoggedIn(): boolean {
          return !!Meteor.user();
      }
  
      goToLoginForm(): void {
          this.router.navigateByUrl('/login');
      }
  
      logout(): void {
          Meteor.logout((error) =&gt; {
              if (error) {
                  console.log(error);
              } else {
                  this.router.navigateByUrl("/");
              }
          });
      }
  }
  </code></pre>
  
  <p>I'm sure I am missing something really simple, but it eludes me.  All help is appreciated.</p>