Bug#1034607: xfce4-screensaver vs light-locker

[Brandon Werner]

Hello,
I did an install of xfce with the daily netinst image to test this change to 
tasksel. I ended up with both light-locker and xfce4-screensaver installed. I 
think this may be because the control file for xfce4-session lists light-locker 
first in the screensavers it recommends but I am not sure.