adding ts-node as dev dependency so that we can run unit tests individually

Author: thechenky

package.json

@@ -47,6 +47,7 @@
     "nock": "^9.0.0",
     "prettier": "^1.13.7",
     "sinon": "^1.17.4",
+    "ts-node": "^7.0.1",
     "typescript": "~2.8.3"
   },
   "peerDependencies": {