Python API doesn't expose OlaClient's close_callback

[rbalykov]

systemctl restart olad - crashes python client.
this workaround does fine:

class PatchedClientWrapper(ClientWrapper):
def init(self, socket=None, close_callback=None):
self._ss = SelectServer()
self._client = OlaClient(our_socket=None, close_callback=_on_olad_socket_close)
self._ss.AddReadDescriptor(
self._client.GetSocket(),
self._client.SocketReady
)