Fix #1625, add /contribute.json
Fix #1625, add /contribute.json

fzzzy/pageshot,fzzzy/pageshot,mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/screenshots,mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/pageshot,fzzzy/pageshot,fzzzy/pageshot,mozilla-services/screenshots,mozilla-services/pageshot