Enable localhost login without password using VimSessionOrientedStub

[jcasale]

I am trying to convert a script that uses SmartConnect over to VimSessionOrientedStub based on #347.

SmartConnect allows a localhost login for root without a password, is it possible to do the same with VimSessionOrientedStub?

For example:

soap_stub = SmartStubAdapter(host='localhost', port=443)
session_stub = VimSessionOrientedStub(soap_stub, VimSessionOrientedStub.makeUserLoginMethod('root', None))
service_instance = vim.ServiceInstance('ServiceInstance', session_stub)