Make notification example code Swift 1.2 compliant

README.md

@@ -43,7 +43,7 @@ and
 
     func reachabilityChanged(note: NSNotification) {
 
-        let reachability = note.object as Reachability
+        let reachability = note.object as! Reachability
 
         if reachability.isReachable() {
             if reachability.isReachableViaWiFi() {