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

lib/pcsclite.js

@@ -36,12 +36,17 @@ module.exports = function() {
                         var r = new CardReader(name);
                         readers_aux.push(r);
                         p.emit('reader', r);
-                        r.get_status(function(e, status) {
+                        r.get_status(function(e, state, atr) {
                             if (e) {
                                 r.emit('error', e);
                             } else {
+                                var status = { state : state };
+                                if (atr) {
+                                    status.atr = atr;
+                                }
+
                                 r.emit('status', status);
-                                r.status = status;
+                                r.state = state;
                             }
                         });
                     }