title: Problem with toastr doesn't work sometimes
body: <p>sometimes the toastr in angular doesn't work until i reload the page and the html element toast-container doesn't exist in html until i reload:</p>
  
  <p>import:</p>
  
  <pre><code>import { ToastsManager } from 'ng2-toastr';
  ....
  constructor(public toastr: ToastsManager){}
  ...
  if (bDm === false) {
    this.toastr.warning('xxxx', 'yyyy');
    return false;
  }
  </code></pre>
  
  <p>in app.modules</p>
  
  <pre><code>import { ToastModule, ToastOptions } from 'ng2-toastr/ng2-toastr';
   ....
   imports: [
  ToastModule.forRoot()
  ]
  </code></pre>
  
  <p>and in package.json i've got:</p>
  
  <pre><code>"ng2-toastr": "^4.1.2",
  </code></pre>
  
  <p>By the way the navigator i use is google chrome and no errors appairs in console.</p>
  
  <p>Best regards!</p>