add socket_io_common dependency

Author: jumperchen

lib/socket_io.dart

@@ -7,4 +7,4 @@ export 'src/engine/transport/jsonp_transport.dart' show JSONPTransport;
 export 'src/engine/transport/polling_transport.dart' show PollingTransport;
 export 'src/engine/transport/websocket_transport.dart' show WebSocketTransport;
 
-export 'package:socket_io/src/engine/parser/parser.dart' show PacketParser;
+export 'package:socket_io_common/src/engine/parser/parser.dart' show PacketParser;

lib/src/adapter/adapter.dart

@@ -12,7 +12,7 @@
  */
 import 'dart:async';
 import 'package:socket_io/src/namespace.dart';
-import 'package:socket_io/src/parser/parser.dart';
+import 'package:socket_io_common/src/parser/parser.dart';
 import 'package:socket_io/src/util/event_emitter.dart';
 
 abstract class Adapter {

lib/src/client.dart

@@ -13,7 +13,7 @@
 import 'package:logging/logging.dart';
 
 import 'package:socket_io/src/engine/socket.dart';
-import 'package:socket_io/src/parser/parser.dart';
+import 'package:socket_io_common/src/parser/parser.dart';
 import 'package:socket_io/src/server.dart';
 
 class Client {