fix(package): update react-dom to version 16.3.2

Closes #39

Author: greenkeeper[bot]

package.json

@@ -8,7 +8,7 @@
   },
   "dependencies": {
     "react": "^15.4.0",
-    "react-dom": "^15.4.0",
+    "react-dom": "^16.3.2",
     "react-router": "^4.0.0",
     "react-router-dom": "^4.0.0"
   },