Add version number 4.3.

Author: jianjunz

peerserver.js

@@ -73,6 +73,7 @@ function authorization(socket, next){
   switch(clientVersion){
     case '4.2':
     case '4.2.1':
+    case '4.3':
       // socket.user stores session related information.
       if(token){
         validateUser(token, function(uid){  // Validate user's token successfully.