TOTPRadius upgrade package

This package will upgrade TOTPRadius v0.2.7, v0.2.8 or v0.2.9 to v0.3 without the need of redeploying the virtual appliance.

Upgrade procedure:
- Take a snapshot or a backup of the appliance
- Upload the contents of the archive to /home/totpradius/upgrade folder (so a copy of this file can be found under the /home/totpradius/upgrade/README.txt path
- Login using SSH and change the current directory to /home/totpradius/upgrade folder
- Change the permission of upgrade.sh script to 755 ("chmod 755 _upgrade.sh")
- Run the upgrade.sh script as a superuser ("sudo ./_upgrade.sh")
- Make sure the upgrade process completes with no errors
- Restart the appliance
- Test the functionality
- Remove the upgrade folder

It is recommended to update the operating system before upgrading the appliance. 
Updates are done using the commands below:
sudo apt update
sudo apt upgrade
