fix string index out of range in local.py line 107

Hi,

When local client close socks5 connection the local.py will receive zero length `data` 

This is the error:

    Exception happened during processing of request from ('192.x.x.x', 62856)
    Traceback (most recent call last):
      File "/usr/lib/python2.6/SocketServer.py", line 558, in process_request_thread
        self.finish_request(request, client_address)
      File "/usr/lib/python2.6/SocketServer.py", line 320, in finish_request
        self.RequestHandlerClass(request, client_address, self)
      File "/usr/lib/python2.6/SocketServer.py", line 615, in __init__
        self.handle()
      File "local.py", line 107, in handle
        mode = ord(data[1])
    IndexError: string index out of range
    ----------------------------------------


This small patch fix this problem :D