* ws4py.server.geventserver.WebSocketServer can now be used as the server
  from gevent-websocket

* Made middleware call the application if the request is regular HTTP and
  not WebSocket.

* Converted UpgradableWSGIHandle into something more simpler, that just
  exposes the underline socket always and gives application means to take
  ownership of it.

  This works as following:
  1) UpgradableWSGIHandle sets environ['wsgi.socket'] to connection's socket.
  2) After the application is done, UpgradableWSGIHandle checks if
     environ['wsgi.socket.detach'] flag is set. If it is, it silently exits
     without processing application's return value, reading/writing anything
     from the socket. The socket is not closed by the server.

  This functionality probably can be moved into gevent server. It can also be
  implemented by other servers.

* Switched arguments: replaced APP(websocket, environ) with APP(environ, websocket)
  That way the same application callable can be used for HTTP and WebSocket apps.