upgrade jwt library

Author: jfromaniello

package.json

@@ -36,7 +36,7 @@
   "dependencies": {
     "async": "^1.5.0",
     "express-unless": "^0.3.0",
-    "jsonwebtoken": "^5.0.0",
+    "jsonwebtoken": "~6.2.0",
     "lodash.set": "^4.0.0"
   },
   "devDependencies": {