This patch provides python client code (and tests) for the subcas feature, as based on Fraser's patches. Those need to be applied to the server code in order for this functionality to be tested. Right now, as per Fraser's patches, there is only support for aid, parent_aid, dn, description. No support yet for cacert and intermediates, or for status. The patch does include unit tests -- which should be required from now on for new python code -- as well as some functional test code - which can later be moved into a functional test framework. Please review. Ade