Updated gitignore

packages/zefyr/.gitignore

 example/ios/Flutter/Generated.xcconfig
 doc/api/
 build/
+
+example/feather

packages/zefyr/example/lib/main.dart

 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 import 'package:flutter/material.dart';
-
-import 'src/full_page.dart';
 import 'src/form.dart';
+import 'src/full_page.dart';
 
 void main() {
   runApp(new ZefyrApp());