Fix #869, obscure shot URLs that are given to GA
Fix #869, obscure shot URLs that are given to GA

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