title: Validate Email in Angular 2
body: <p>If i want to create a directive which validates my email, how to do it? </p>
  
  <pre><code>import { Directive } from '@angular/core';
  
  @Directive({
    selector: '[appEmailValidator]'
  })
  
  export class EmailValidatorDirective {
  
    constructor() {}
  }
  </code></pre>
  
  <p>Created the directive, but have no idea how to implement validation rules/messages. </p>