fix(package): update react-intl to version 4.5.9

Closes #352

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
     "react-ga": "^2.4.1",
     "react-headroom": "^2.2.2",
     "react-helmet": "^5.2.0",
-    "react-intl": "^2.4.0",
+    "react-intl": "^4.5.9",
     "react-redux": "^5.0.7",
     "react-router": "^4.2.0",
     "react-router-dom": "^4.2.2",