I'm currently planning to migrate (again) to a +Raspberry Pi 2 because my +Cubietruck Cubieboard3 is a bit nasty concerning port forwarding. It doesn't show up in my Fritz!Box so I cannot redirect the ports in a convenient way.
Again I updated my script for getting +Kolab and it should handle all the dependencies in the right way so that you will be able to install it via "apt-get" or "aptitude".
So feel free to get it from my site and test it.
And I will switch from Apache to NginX as a Webserver and IMAP-Proxy as well.
So come back again for updates