Adding Linux Mint Qiana Repositories to Ubuntu or Ubuntu derivative installation avoiding GPG error

I use a lot some of the Linux Mint packages like USB Image Writer and USB Stick formatter. I added the Linux Mint LTS release (Qiana or Mint 17) repositories to my Linux Lite 2.0 installation by running the following codes through the terminal:

$ sudo sh -c 'echo "deb http://packages.linuxmint.com/ qiana main" >> /etc/apt/sources.list.d/mint.list'

Now run an update.

$ sudo apt-get update