add test-headless

Author: jojozhuang

package.json

@@ -15,6 +15,7 @@
     "build-nas": "ng build --configuration nas",
     "start-nas": "ng serve --configuration nas",
     "test": "ng test",
+    "test-headless": "ng test --watch=false --browsers=ChromeHeadless",
     "lint": "ng lint",
     "e2e": "ng e2e"
   },