fix whitespaces
fix the correct remote address

The remote address should return the direct client addr not a forwarded
header.

This is a breaking change. The main problem with such changes is the way
the application or framework will handle the URL completion. Indeed most
of them are only expecting a TCP socket.

fix #633
dont' override SERVER_* by the Host header

Gunicorn shouln't override the SERVER_* by the Host header. The client
will take care about it during the URL reconstruction if needed.

Since the spec don't support unix sockets, Gunicorn is using the HOST
heeader when available to create viable SERVER_* if possible so the
application and framworks will be happy. When the Host Header is not
available (SocketPath, '') is returned.

fix #628