add page of fcs

lib/model/shipment_rate_model.dart

@@ -0,0 +1,34 @@
+import 'dart:async';
+
+import 'package:cloud_firestore/cloud_firestore.dart';
+import 'package:fcs/vo/rate.dart';
+import 'package:logging/logging.dart';
+
+import 'base_model.dart';
+
+class ShipmentRateModel extends BaseModel {
+  final log = Logger('ShipmentRateModel');
+
+  StreamSubscription<QuerySnapshot> listener;
+
+  List<Rate> rates = [
+    Rate(
+        id: '1', name: 'general_cargo', description: 'General Cargo', price: 6),
+    Rate(id: '2', name: 'medicine', description: 'Medicine', price: 7),
+    Rate(
+        id: '3',
+        name: 'dangerous_cargo',
+        description: 'Dangerous Cargo',
+        price: 8),
+  ];
+
+  void initUser(user) {
+    super.initUser(user);
+  }
+
+  @override
+  logout() async {
+    if (listener != null) await listener.cancel();
+    rates = [];
+  }
+}