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
Updated tests for Iq stanzas to not start a stream for every test; tests now run a lot faster.
The call to streamClose must still be in the tearDown method to ensure it is called in the
case of an error.
