fix(package): update mobx-react to version 5.3.4

Closes #15

Author: greenkeeper[bot]

package.json

@@ -13,7 +13,7 @@
   "dependencies": {
     "express": "^4.13.4",
     "mobx": "^3.2.1",
-    "mobx-react": "^4.2.2",
+    "mobx-react": "^5.3.4",
     "react": "^15.6.1",
     "react-dom": "^15.6.1",
     "react-router": "^4.1.2",