Merge pull request kunalkapadia#132 from KunalKapadia/greenkeeper-winston-2.3.0

Update winston to version 2.3.0 🚀

Author: kunalkapadia

package.json

@@ -54,7 +54,7 @@
     "method-override": "^2.3.5",
     "mongoose": "4.6.6",
     "morgan": "1.7.0",
-    "winston": "2.2.0"
+    "winston": "2.3.0"
   },
   "devDependencies": {
     "babel-cli": "6.18.0",