Cosmetics: Exception when ServiceFault instead of PublishRepsonse arrives

[jk987]

http://ulozto.net/xiWcarrj/20151028-servicefault-instead-of-publishresponse-pcapng
password: ua1234

After I delete subscription (I'm doing this before disconnecting client) I can find following exception in log:

2015-10-28 10:11:39,013 - concurrent.futures - ERROR - exception calling callback for <Future at 0x546c870 state=finished returned Buffer>
Traceback (most recent call last):
File "C:\Python27\lib\site-packages\concurrent\futures_base.py", line 298, in _invoke_callbacks
callback(self)
File "C:\Python27\lib\site-packages\opcua\binary_client.py", line 330, in _call_publish_callback
response = ua.PublishResponse.from_binary(future.result())
File "C:\Python27\lib\site-packages\opcua\uaprotocol_auto.py", line 10434, in from_binary
obj.Parameters = PublishResult.from_binary(data)
File "C:\Python27\lib\site-packages\opcua\uaprotocol_auto.py", line 10383, in from_binary
obj.SubscriptionId = unpack_uatype('UInt32', data)
File "C:\Python27\lib\site-packages\opcua\uatypes.py", line 134, in unpack_uatype
return struct.unpack(fmt, data.read(size))[0]
File "C:\Python27\lib\site-packages\opcua\utils.py", line 39, in read
raise Exception("No enough data left in buffer, request for {}, we have {}".format(size, self))
Exception: No enough data left in buffer, request for 4, we have Buffer(size:0, data:)

I doesn't bother me much because it is handled somewhere inside so my app doesn't know about this. That's why I didn't investigate it very much.
I only think that this happens when BinaryClient is expecting PublishResponse but he gets ServiceFault packet.

Here is another capture when I didn't call subscription.delete before client.disconnect:
http://ulozto.net/xDundii7/20151028-servicefault-instead-of-publishresponse-v2-pcapng

I humbly suggest that the message in log could be more accurate. It's not the problem "No enough data left...".

Maybe it is similar to issue #29. (?)

[oroulet]

kepware sends extra notifications after session is closed!!! I added a line to parse for that and print a bit better warning