> Made script more robust against failures:
> 1) added test for internet connectivity
> 2) check that time and date is correct
>     or apt update will fail. Fix it 
>     with ntpdate-debian if not correct 
> 2) added test to check that required deb packages 
>     download really succeeds
> 3) Move point of no return further down the script
>     after most of the checks for prerequisites 
>     by reshuffling the code a little bit
> 4) remove full paths of programs (as they can
>     be different between systems) with the 
>      exception of /bin/echo (don't want builtin)