Refactor install.sh to actually work on a Ubuntu server

I found that the installation script doesn't quite work, so it won't work by just running `bash ./install.sh` on a newly installed Ubuntu server.  For instance, the ordering of some commands might be wrong: `mv Result.sh /var/log/NTUticket` should appear after `mkdir /var/log/NTUticket`...

Anyway, I decided to refactor this small script and add some helping features in case the user forgets to become root first, forgets to check networking, forgets to have some required files, etc.  Check this out and see if it's helpful or not.