fix(build-storybook): building a storybook static site still requires test-utils

Author: travi

package.json

@@ -81,6 +81,7 @@
     "nyc": "10.2.0",
     "prop-types": "15.5.8",
     "react": "15.5.4",
+    "react-addons-test-utils": "15.5.1",
     "react-helmet": "5.0.3",
     "react-test-renderer": "15.5.4",
     "rimraf": "2.6.1",