Update legacy auth to be used outside of stream features.

Also, add detection of legacy XMPP version.

sleekxmpp/basexmpp.py

@@ -212,6 +212,10 @@ class BaseXMPP(XMLStream):
         self.stream_version = xml.get('version', '')
         self.peer_default_lang = xml.get('{%s}lang' % XML_NS, None)
 
+        if not self.is_component and not self.stream_version:
+            log.warning('Legacy XMPP 0.9 protocol detected.')
+            self.event('legacy_protocol')
+
     def process(self, *args, **kwargs):
         """Initialize plugins and begin processing the XML stream.