* block and unblock ipv6 explicitly
* refactor admin api tests
* use sendAdminPayload() for chatuser tests
* fix sendAdminRequests
* add getAdminResponse() to api test lib/admin.js
* some admin apis don't have response body
* cleanup test/automated/api/chatusers.test.js
* cleanup test/automated/api/chatusers.test.js
use getAdminResponse() to access admin apis