Added United States Social Security Administration

See #448
Added image for US SSA
Renamed US SSA image
Added Desura to gaming.yml
Renamed FFXIV into SquareEnix in gaming.yml
Merge pull request #461 from mxxcon/SquareEnix

Renamed FFXIV into SquareEnix in gaming.yml
Merge pull request #460 from mxxcon/Desura

Added Desura to gaming.yml
Updating Duo Security entry

Just a quick edit to list our formal name, "Duo Security" rather than the existing shorthand, "Duo".
Merge pull request #463 from mstanislav/patch-1

Updating Duo Security entry
Fix links in README/CONTRIBUTING
Merge pull request #458 from jamcat22/patch-6

Added United States Social Security Administration