(#18): setter to change visible health

frontend/core/src/com/game/tankwars/view/GameHud.java

@@ -116,4 +116,20 @@ public class GameHud {
     public Button getMoveRight() {
         return moveRight;
     }
+
+    /**
+     * Set visible health of player
+     * @param health new health of player
+     */
+    public void setPlayerHealth(int health) {
+        healthProgressBarPlayer.setValue(health);
+    }
+
+    /**
+     * Set visible health of opponent
+     * @param health new health of opponent
+     */
+    public void setOpponentHealth(int health) {
+        healthProgressBarOpponent.setValue(health);
+    }
 }