updated typescript version

Author: sevensc

package-lock.json

@@ -37,7 +37,7 @@
     "mocha": "^3.4.2",
     "pump": "^2.0.1",
     "ts-node": "^3.2.0",
-    "typescript": "^2.7.1"
+    "typescript": "^2.8.1"
   },
   "directories": {
     "test": "tests"