chore(package): update react-router to version 2.4.0

https://greenkeeper.io/

package.json

@@ -120,7 +120,7 @@
     "react": "15.0.1",
     "react-cookie": "0.4.5",
     "react-redux": "4.4.5",
-    "react-router": "2.3.0",
+    "react-router": "2.4.0",
     "redux": "3.5.2",
     "redux-async-connect": "1.0.0-rc4",
     "redux-logger": "2.6.1",