mailman: add IPv6 support to lighttpd

AAAAs to lists were added today. See
http://redmine.lighttpd.net/projects/lighttpd/wiki/IPv6-Config

Unfortunately sodium is lucid, which means 1.4.26, so this was a bit
hacky. This needs to be revisited when we upgrade.

Bug: 22028
Change-Id: I59a92c5399098da80121406518d0acefaa6592fd
Merge "mailman: add IPv6 support to lighttpd" into production