fix(package): update react-addons-css-transition-group to version 15.4.2 (#1576)
fix(package): update react-addons-css-transition-group to version 15.4.2 (#1576)

https://greenkeeper.io/
kumar303/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,tsl143/addons-frontend,mozilla/addons-frontend,kumar303/addons-frontend,mozilla/addons-frontend,jasonthomas/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,squarewave/addons-frontend,jasonthomas/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,mozilla/addons-frontend,aviarypl/mozilla-l10n-addons-frontend,squarewave/addons-frontend,squarewave/addons-frontend,jasonthomas/addons-frontend,tsl143/addons-frontend,tsl143/addons-frontend,kumar303/addons-frontend,mozilla/addons-frontend,tsl143/addons-frontend,kumar303/addons-frontend