add missing timekeeper package

services/document-updater/package.json

@@ -35,6 +35,7 @@
     "grunt-execute": "~0.1.5",
     "grunt-forever": "^0.4.7",
     "grunt-mocha-test": "~0.9.0",
-    "grunt-shell": "^1.3.0"
+    "grunt-shell": "^1.3.0",
+    "timekeeper": "^2.0.0"
   }
 }