====== Configure lightdm ======
Ubuntu 14.04

After remove unity and install xfce4 we still need to configure lightdm

Install lightdm greeter:

    apt-get install  lightdm-gtk-greeter
    
Configure lightdm
    cat /etc/lightdm/lightdm.conf.d/50-imovefan.conf 
    [SeatDefaults]
    greeter-session=lightdm-gtk-greeter
    user-session=xfce4