chore(package): update mobx to version 2.5.1

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -57,7 +57,7 @@
   "dependencies": {
     "ajv": "4.6.1",
     "lodash": "4.15.0",
-    "mobx": "2.5.0"
+    "mobx": "2.5.1"
   },
   "devDependencies": {
     "babel-cli": "6.14.0",