Adding shrine. (#3)

Adds a new version of Shrine from the MDC codelabs.

shrine/lib/main.dart

@@ -0,0 +1,31 @@
+// Copyright 2018-present the Flutter authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'package:flutter/material.dart';
+import 'package:scoped_model/scoped_model.dart';
+
+import 'app.dart';
+import 'model/app_state_model.dart';
+
+void main() {
+  AppStateModel model = AppStateModel();
+  model.loadProducts();
+
+  runApp(
+    ScopedModel<AppStateModel>(
+      model: model,
+      child: ShrineApp(),
+    ),
+  );
+}