Angular Tour of heroes: ai continué sur HTTP

* ajout d'un héro
  * suppression d'un héro
  * mise à jour d'un héro

angular-tour-of-heroes/src/app/heroes/heroes.component.html

@@ -1,10 +1,21 @@
 <h2>My Heroes</h2>
 
+<div>
+  <label>Hero name:
+    <input #heroName />
+  </label>
+  <!-- (click) passes input value to add() and then clears the input -->
+  <button (click)="add(heroName.value); heroName.value=''">
+    add
+  </button>
+</div>
 
 <ul class="heroes">
   <li *ngFor="let hero of heroes">
     <a routerLink="/detail/{{hero.id}}">
       <span class="badge">{{hero.id}}</span> {{hero.name}}
     </a>
+    <button class="delete" title="delete hero"
+      (click)="delete(hero)">x</button>
   </li>
 </ul>