src: fix for OSs not supporting PnP Notification

- Instead of waiting for the notification, it will poll every second for a new
  card reader.
- Thanks to Ludovic Rousseau for the help. See:
  https://github.com/santigimeno/node-pcsclite/issues/14

src/pcsclite.h

@@ -49,8 +49,10 @@ class PCSCLite: public node::ObjectWrap {
     private:
 
         SCARDCONTEXT m_card_context;
+        SCARD_READERSTATE m_card_reader_state;
         pthread_t m_status_thread;
         pthread_mutex_t m_mutex;
+        bool m_pnp;
 };
 
 #endif /* PCSCLITE_H */