Add the option so that the script can self update.

[Akarshit]

The script should check if some update is available to it and should automatically update itself when connected to internet. It is just a matter of cloning this repo again, modifying the permission of installation script(which the old script can do as it already has permission), running the new script and then the new script deleting the old one.

[clearnote01]

#17 added this feature.
Can close this issue now