Fix for:
  File /var/lib/python2.7/site-packages/gevent_socketio-0.3.6-py2.7.egg/socketio/handler.py",
line 184, in handle_one_response
    del self.websocket.environ
AttributeError: environ
Merge pull request #172 from arnuschky/fix-websocket.environ

Fix for AttributeError: environ