fixes for the gevent backend

- the client address (i.e. REMOTE_ADDR) in the wsgi environment was
always wrong (which made it hard to use things like
django-debug-toolbar). We need to compare the server.address_family,
NOT the server.socket_type for that check.

- Pass the right handler class down to the gevent Server type, as
this wasn't getting passed down
Merge pull request #52 from wynnw/feature/gevent-backend-fixes

fixes for the gevent backend