Merge branch '192-sanitizer-for-quiz-now' into 'staging'

Adds sanitizer to make dom cors access possible with observables

Closes #192

See merge request arsnova/topic-cloud!102

src/app/components/shared/quiz-now/quiz-now.component.html

 <div class="container">
-  <iframe class="responsive-iframe" src="https://arsnova.click"></iframe>
+  <iframe class="responsive-iframe" src="urlSafe"></iframe>
 </div>

src/app/components/shared/quiz-now/quiz-now.component.ts

 import { Component, OnInit } from '@angular/core';
+import { DomSanitizer, SafeResourceUrl } from '@angular/platform-browser';
 
 @Component({
   selector: 'app-quiz-now',
@@ -7,9 +8,13 @@ import { Component, OnInit } from '@angular/core';
 })
 export class QuizNowComponent implements OnInit {
 
-  constructor() { }
+  url = 'https://arsnova.click';
+  urlSafe: SafeResourceUrl;
+
+  constructor(public sanitizer: DomSanitizer) { }
 
   ngOnInit(): void {
+    this.urlSafe = this.sanitizer.bypassSecurityTrustResourceUrl(this.url);
   }
 
 }