add express-validator, add body parser middleware, support some more errors in error handler middleware

package.json

@@ -24,6 +24,7 @@
     "estraverse": "^4.1.1",
     "express": "~4.13.3",
     "express-csv": "~0.6.0",
+    "express-validator": "^2.18.0",
     "firebase": "^2.2.9",
     "firebase-token-generator": "^2.0.0",
     "glob": "^4.3.5",
@@ -82,7 +83,7 @@
     "superagent": "~1.4.0",
     "swagger-node-express": "lefnire/swagger-node-express#habitrpg",
     "universal-analytics": "~0.3.2",
-    "validator": "~3.19.0",
+    "validator": "~4.2.1",
     "winston": "~2.0.1"
   },
   "private": true,