Fix gunicorn >= 19.0 support in gunicorn worker

[niligulmohar]

With this change the socket.socket API is used directly for sockets that
don't have any version of the gunicorn.sock.BaseSocket address
attribute, which is necessary since gunicorn 19.0 and this commit:

benoitc/gunicorn@9a83d71

[niligulmohar]

... and now i found #211 😓

Well, i prefer this solution, since it will support any socket.socket like object through duck typing instead of just the gevent.socket.socket variety. Do you have an opinion @jares777?

[jares777]

Yes I agree with you. I am glad to see that there is life again in this package.
I have been using it in production for last one year without any issues.