fix(package): update ts-node to version 6.1.2

Closes #8

Author: greenkeeper[bot]

package.json

@@ -51,7 +51,7 @@
     "@types/jsonwebtoken": "^7.2.5",
     "@types/node": "^9.3.0",
     "typedoc": "^0.10.0",
-    "ts-node": "^4.1.0",
+    "ts-node": "^6.1.2",
     "del-cli": "^1.1.0",
     "class-transformer": "^0.1.8",
     "class-validator": "^0.8.0",