Add support for testing content in SkyView

sky/tests/framework/resources/basic.dart

 import 'dart:sky';
 
 import 'package:sky/framework/fn.dart';
 
 class TestApp extends App {
   UINode build() {
     return new Container(
       inlineStyle: 'background-color: green',
       children: [
         new Text('I am Text'),
         new Image(src: 'resources/united.jpg')
       ]
     );
   }
 }