fix(package): update morgan to version 1.9.1

Closes #18

Author: greenkeeper[bot]

package.json

@@ -14,7 +14,7 @@
     "express-jwt": "^5.1.0",
     "jsonwebtoken": "^7.1.9",
     "mongoose": "^4.6.7",
-    "morgan": "~1.8.0",
+    "morgan": "~1.9.1",
     "passport": "^0.3.0",
     "passport-local": "^1.0.0",
     "serve-favicon": "~2.4.0"