fix shellscript paths for autostart, fix path for manage.py in runatboot.sh

fixes for server start linux scripts - 
a) in autostart mode "service kalite start"
b) when running interactively but outside of the ka-lite working directory.

Also, fix for runatboot.sh which was failing when run interactively because of the path to the manage.py command.

To test, 
i) install a system with autostart set true  (i.e. with a kalite script in etc/init.rc/
ii) try the following commands without this patch:
$ ~/path to ka-lite/start.sh
$ service kalite start
$ sudo ~/path to ka-lite/kalite/runatboot.sh
iii) repeat those commands with the patch - there should be no errors