title: Adding items to array for primeng dropdown does not update the rendred dropdown
body: <p>I'm trying to add a new item to a angular dropdown. </p>
  
  <pre><code>export class ClansOfCaledoniaComponent implements OnInit {
    public selectedGame: ClansGame;
    public games = new Array&lt;ClansGame&gt;();
  
    constructor(private readonly clansOfCaledoniaService: ClansOfCaledoniaService ) { }
  
    ngOnInit() {
      this.clansOfCaledoniaService.getListOfGames().subscribe(r =&gt; {
        this.games = r;
        this.selectedGame = this.games[0];
      });
    }
    newGame() {
      var game = new ClansGame();
      game.name = `Game ${this.games.length + 1}`;
      let p = new Array&lt;ClansPlayer&gt;();
      p.push(new ClansPlayer());
      game.players = p;
      this.clansOfCaledoniaService.save(game).subscribe(a =&gt; {
        game.id = +a.status;
        this.games.push(game);
        this.selectedGame = game;
        console.log(game);
      });
    }
  }
  </code></pre>
  
  <p>The HTMl I'm using </p>
  
  <pre><code>  &lt;div class="ui-g-2"&gt;
      &lt;p-dropdown [options]="games" [(ngModel)]="selectedGame" optionLabel="name"&gt;&lt;/p-dropdown&gt;
    &lt;/div&gt;
    &lt;div class="ui-g-2"&gt;
      &lt;button pButton type="button" label="New game" (click)="newGame()"&gt;&lt;/button&gt;
    &lt;/div&gt;
  </code></pre>
  
  <p>For some reason the dropdown is not updated when I push the new game. How can I update the array ?</p>