Fixed shopping cart not updating when returning to activity

Author: ajungg

ui/src/main/java/io/snabble/sdk/ui/cart/ShoppingCartView.java

@@ -299,6 +299,7 @@ public void onDetachedFromWindow() {
                 public void onActivityStarted(Activity activity) {
                     if (UIUtils.getHostActivity(getContext()) == activity) {
                         registerListeners();
+                        onCartUpdated();
                     }
                 }