title: "Deselect all checkboxes" not working with angular property binding
body: <p>I have used property binding in angular to deselect all checkboxes, but it is not working as expected. 
  What i expected: After selecting one or more checkboxes when i click 'clear' button it should deselect all checkboxes.
  here is my <a href="https://plnkr.co/edit/DiPF9inrqT1uuXFPi94N?p=preview" rel="nofollow noreferrer">plunker</a></p>
  
  <pre><code>isSelected is the boolean variable which i have used to set the 'checked' attribute of checkbox. 
  </code></pre>
  
  <p><strong>template:</strong></p>
  
  <pre><code>&lt;div *ngFor="let item of items"&gt;
      &lt;input [checked]="isSelected" type="checkbox"&gt;{{item}}
  &lt;/div&gt;
  &lt;button (click)="onClear()"&gt;Clear All&lt;/button&gt;
  </code></pre>
  
  <p><strong>Component</strong></p>
  
  <pre><code>private items = ['a', 'b', 'c', 'd'];
    private isSelected = false;
    constructor() {
    }
  
    onClear(){
      this.isSelected = false;
    }
  </code></pre>