lib/apache2: Add WSGI Handler

lib/apache2: Add WSGI Handler

Patchwork/Django can be run directly with WSGI, which is bound to be
faster and less complex than FastCGI. This patch provides the necessary
Apache configuration and the WSGI handler, as well as an update to the
docs.

Since python-flup is deprecated and WSGI supersedes FastCGI, it should
be(come) the preferred method. Hence I documented it first.

For the xmlrpc interface to work with WSGI, the HTTP authorization
information needs to be passed to the WSGI handler. This is done by
setting WSGIPassAuthorization On in the apache2 config file snippet.

Ref: http://www.arnebrodowski.de/blog/508-Django,-mod_wsgi-and-HTTP-Authentication.html

Signed-off-by: martin f. krafft <madduck@madduck.net>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>