Don't configure Raven if there's no Sentry DSN
Don't configure Raven if there's no Sentry DSN

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