Change the directory that /media points to

The /usr/share/pyshared/django/contrib/admin/media/ is the one
that's actually contained in the python-django package - on some
systems with that package installed (e.g. firefly),
/var/lib/python-support/python2.5/django/contrib/admin/media
doesn't exist.  (The Debian packages generate the
/var/lib/python-support structures for the Python versions that
are installed.)

conf/httpd.conf-example

@@ -11,5 +11,5 @@ WSGIProcessGroup example.mapit.mysociety.org
 
 WSGIScriptAlias / /data/vhost/example.mapit.mysociety.org/mapit/web/django.wsgi
 
-Alias /media /var/lib/python-support/python2.5/django/contrib/admin/media
+Alias /media /usr/share/pyshared/django/contrib/admin/media
 Alias /static /data/vhost/example.mapit.mysociety.org/mapit/mapit/static