added react-router

Change-Id: If5b7a1e960acaca805d4f154705cbd2da34acb3f
Reviewed-on: https://gerrit.instructure.com/38084
Reviewed-by: Ryan Shaw <ryan@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Ryan Shaw <ryan@instructure.com>
QA-Review: Ryan Shaw <ryan@instructure.com>