Upgrade 2.2 -> 2.4

[Ondřej Surý]

Hi,

I have just tested the upgrade from 2.2 to 2.4 on my server and it's
still quite complicated even when the spool is empty :-(.

We need to work on that since almost all cyrus-*-2.2 packages were
left in the Install/Conf-files state and purging them removed some
files from -2.4 packages.

I'll try to do more serious testing, but it seems that we will need to
upgrade scripts in 2.2 as well.

Ondrej
-- 
Ondřej Surý <ondrej at sury.org>