Update appdata to comply with new specification

http://blogs.gnome.org/hughsie/2014/05/02/appdata-meet-spdx-spdx-meet-appdata/

Please let me know if I messed up on the project licensing, I was unsure of the vdrift-data license, as the only thing I could find was that "vdrift" was gplv3. The fedora repo shows that "vdrift-data" is GPLv3+ so I went with that.
Merge pull request #134 from davidgumberg/appdat

Update appdata to comply with new specification