Roll Observatory packages and add a roll script

packages/charted/lib/charted.dart

 /*
  * Copyright 2014 Google Inc. All rights reserved.
  *
  * Use of this source code is governed by a BSD-style
  * license that can be found in the LICENSE file or at
  * https://developers.google.com/open-source/licenses/bsd
  */
 /**
  * A library to create visualizations - implementation/port of D3.js in Dart.
  */
 library charted;
 
 export 'charts/charts.dart';
 export 'core/utils.dart';
 export 'core/timer.dart';
 export 'core/interpolators.dart';
 export 'layout/layout.dart';
 export 'core/scales.dart';
 export 'selection/selection.dart';
 export 'selection/transition.dart';
 export 'svg/axis.dart';
 export 'svg/shapes.dart';