Rename the _fletch_system and service and dart: libraries

tests/service_tests/multiple_services/dart/service_one.dart

 // Copyright (c) 2015, the Fletch 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.md file.
 
 // Generated file. Do not edit.
 
 library service_one;
 
 import "dart:fletch";
 import "dart:fletch.ffi";
-import "dart:service" as service;
+import "dart:fletch.service" as service;
 
 final Channel _channel = new Channel();
 final Port _port = new Port(_channel);
 final ForeignFunction _postResult = ForeignLibrary.main.lookup("PostResultToService");
 
 bool _terminated = false;
 ServiceOne _impl;
 
 abstract class ServiceOne {
   int echo(int arg);
@@ skipping 24 matching lines @@
         _postResult.vcall$1(request);
         break;
       default:
         throw new UnsupportedError("Unknown method");
     }
   }
 
   static const int _TERMINATE_METHOD_ID = 0;
   static const int _ECHO_METHOD_ID = 1;
 }