fix backwards compatible problems with python-engineio 3.0

Author: miguelgrinberg

socketio/middleware.py

@@ -39,3 +39,7 @@ def __init__(self, socketio_app, wsgi_app=None, static_files=None,
 
 class Middleware(WSGIApp):
     """This class has been renamed to WSGIApp and is now deprecated."""
+    def __init__(self, socketio_app, wsgi_app=None,
+                 socketio_path='socket.io'):
+        super(Middleware, self).__init__(socketio_app, wsgi_app,
+                                         socketio_path=socketio_path)

socketio/tornado.py

@@ -1,7 +1,11 @@
 import sys
 if sys.version_info >= (3, 5):
-    from engineio.async_tornado import get_tornado_handler as \
-        get_engineio_handler
+    try:
+        from engineio.async_drivers.tornado import get_tornado_handler as \
+            get_engineio_handler
+    except ImportError:
+        from engineio.async_tornado import get_tornado_handler as \
+            get_engineio_handler
 
 
 def get_tornado_handler(socketio_server):