Decouple WifiInterface from Parser

This removes the need for WifiInterfrace <+> command processing to be included in the link. so parser does not need to see the config settings for wifi.
If Wifi doesnt set the At command callback, parser will return <X> for a <+> command

WifiInterface.cpp

@@ -60,6 +60,8 @@ bool WifiInterface::setup(Stream & setupStream,  const __FlashStringHelper* SSid
     checkForOK(200, OK_SEARCH, true);      
   }
   streamer=new MemStream(buffer, MAX_WIFI_BUFFER);
+  parser.setAtCommandCallback(ATCommand);
+  
   DIAG(F("\n++ Wifi Setup %S ++\n"), connected ? F("OK") : F("FAILED"));
   return connected;
 }