Reorganize mdv and observe packages

pkg/mdv/test/observe_utils.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
-library mdv_observe_utils;
+library observe_utils;
 
-import 'package:mdv_observe/mdv_observe.dart';
+import 'package:observe/observe.dart';
 
 toSymbolMap(Map map) {
   var result = new ObservableMap.linked();
   map.forEach((key, value) {
     if (value is Map) value = toSymbolMap(value);
     result[new Symbol(key)] = value;
   });
   return result;
 }