* python/dbus_bindings.pyx (String, MessageIter): make D-Bus strings
derive from unicode instead of str, and encode/decode UTF-8 when
marshalling/unmarshalling bus messages
* python/introspect_parser.py: encode introspection data as UTF-8
before passing the buffer into libxml2
* test/python/test-client.py: add unicode test strings
* test/data/valid-service-files/.cvsignore, test/python/.cvsignore:
ignore generated python test files