[Duplicate] Add a repository by apturl, as easily as installing a package

****Sorry, I realized this is a duplicate. I will keep the content here though:

Make an easy way to add a repository. One would click on a url, a popup would show up saying "do you trust this repository?" would show up, and if "yes" is clicked, then a line is added to /etc/apt/sources.list.d/apturl.list, and a key is added to the keyring.

For example:
apt:repo(deb http://download.virtualbox.org/virtualbox/debian/ jaunty non-free),key(http://download.virtualbox.org/virtualbox/debian/sun_vbox.asc),virtualbox-3.0

First it adds a third-party repository, then the key associated with it, then installs the package "virtualbox-3.0".

This is similar to https://wiki.ubuntu.com/FoundationsTeam/Specs/KarmicAptUrlPpaPolicy and http://doctormo.wordpress.com/2009/06/01/ubuntu-apt-url-and-the-white-list/, except those only look at PPAs.