CardReader status event should return the ATR

- Of the inserted card.
- Refactoring of the code that creates a Buffer instance into a
  separate function.
- Update the example and README
- It fixes bug #2

src/cardreader.h

@@ -41,6 +41,8 @@ class CardReader: public node::ObjectWrap {
     struct AsyncResult {
         LONG result;
         unsigned long status;
+        unsigned char atr[MAX_ATR_SIZE];
+        unsigned long atrlen;
         bool do_exit;
     };
 
@@ -80,6 +82,8 @@ class CardReader: public node::ObjectWrap {
         static void AfterTransmit(uv_work_t* req);
         static void CloseCallback(uv_handle_t *handle);
 
+        static v8::Handle<v8::Value> CreateBufferInstance(char* data, unsigned long size);
+
     private:
 
         SCARDCONTEXT m_card_context;