Support is only for adding literal XML content
to stanzas. Full support for things like multiple
message bodies with different xml:lang values is
still in the works.
Moved SleekTest to sleekxmpp.test.
Organized test suites by their focus.
- Suites focused on testing stanza objects are named test_stanza_X.py
- Suites focused on testing stream behavior are name test_stream_X.py