Fix example code.

And try testing things in future...

Closes #8.

README.md

@@ -13,7 +13,7 @@ pcars is a Python client for the Project CARS UDP data stream.
 from pcars.stream import PCarsStreamReceiver
 
 class MyPCarsListener(object):
-    def handlePacket(data):
+    def handlePacket(self, data):
         # You probably want to do something more exciting here
         # You probably also want to switch on data.packetType
         # See listings in packet.py for packet types and available fields for each