Move Yaml into utils/pub.

utils/pub/pub.dart

 // Copyright (c) 2012, 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.
 
 /**
  * The main entrypoint for the pub command line application.
  */
 #library('pub');
 
-#import('../yaml/yaml.dart');
+#import('yaml/yaml.dart');
 
 #import('io.dart');
 #import('utils.dart');
 
 #source('cache.dart');
 #source('command_list.dart');
 #source('command_update.dart');
 #source('command_version.dart');
 #source('package.dart');
 
@@ skipping 110 matching lines @@
     cache = cache_;
 
     // TODO(rnystrom): Each command should define the arguments it expects and
     // we can handle them generically here.
 
     onRun();
   }
 
   abstract void onRun();
 }