Roll Observatory packages and add a roll script

packages/args/lib/command_runner.dart

 // Copyright (c) 2014, 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 args.command_runner;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:math' as math;
 
@@ skipping 362 matching lines @@
   var buffer =
       new StringBuffer('Available ${isSubcommand ? "sub" : ""}commands:');
   for (var name in names) {
     buffer.writeln();
     buffer.write('  ${padRight(name, length)}   '
         '${commands[name].description.split("\n").first}');
   }
 
   return buffer.toString();
 }