update package.json to use the last version of grunt-ts

Author: OlegKi

package.json

@@ -69,7 +69,7 @@
     "grunt-jscs": "^3.0.1",
     "grunt-newer": "^1.3.0",
     "grunt-replace": "^1.0.1",
-    "grunt-ts": "^6.0.0-beta.15",
+    "grunt-ts": "^6.0.0-beta.16",
     "grunt-tslint": "^5.0.1",
     "tslint": "^5.3.2",
     "tslint-eslint-rules": "^4.1.1",