Fix bug 918696 - White backgrounds for transparent thumbnails
Fix bug 918696 - White backgrounds for transparent thumbnails

mozilla/webmaker.org,mozilla/webmaker.org,mmmavis/webmaker.org,alicoding/webmaker.org,alicoding/webmaker.org,mmmavis/webmaker.org,jbuck/webmaker.org,cadecairos/webmaker.org,cadecairos/webmaker.org