Bug#1029557: debian-edu-config: Session exits on first login on roaming-workstation fails

[Guido Berhoerster <guido@berhoerster.name>]

This is actually a bug in LightDM which makes assumptions about the home 
directory not changing and hardcoding paths to the Xauthority file.

There is also a small fix for libpam-mklocaluser necessary so it runs 
before the pam_systemd module so that systemd/DBus started processes 
have the correct home directory.

If you want to test, you need to rebuild lightdm with the patch from
https://github.com/canonical/lightdm/pull/323 and change the 
libpam-mklocaluser pam-config priority.

The latter is necessary for other display managers as well.

-- 
Guido Berhoerster