[avatars] Serve 1px transparent GIF instead of 404
[avatars] Serve 1px transparent GIF instead of 404

PriviPK/privipk-webapp,PriviPK/privipk-webapp,PriviPK/privipk-webapp,Eagles2F/inbox-scaffold-html5,PriviPK/privipk-webapp,Eagles2F/inbox-scaffold-html5,Eagles2F/inbox-scaffold-html5,nylas/inbox-scaffold-html5,nylas/inbox-scaffold-html5,nylas/inbox-scaffold-html5