Get WarningPolicy working in this example

Using this as an example, I was getting the following error:

  File "cs4224_connector.py", line 31, in __init__
    self.m_ssh.connect(g_host, g_port, username=g_user, password=g_password)
  File "C:\Python27\lib\site-packages\paramiko\client.py", line 321, in connect
    self._policy.missing_host_key(self, server_hostkey_name, server_key)
TypeError: unbound method missing_host_key() must be called with WarningPolicy instance as first argument (got SSHClient
 instance instead)

This commit should fix it.