General bugfixes.
    
    - don't build X.Org devel docs (#755782)
    - applet: BR generic java-devel instead of java-gcj-devel (#755783)
    - use runuser to start Xvnc in systemd service file (#754259)
    - don't attepmt to restart Xvnc session during update/erase (#753216)
    
    Signed-off-by: Adam Tkac <atkac@redhat.com>