[Mailman] Update Mailman to 2.1.19

[Dirk Stöcker]

Hello,

I'm currently in the process of implementing DKIM and DMARC and noticed, 
that OSM mailinglists, especially josm-dev in my case, break correct 
signatures.

Would it be possible to update to version 2.1.19 of the mailman software 
which allows better settings to work properly with signed messages?

Ciao
-- 
http://www.dstoecker.eu/ (PGP key available)