Webhooks - administrative change trigger

[AngusHooper1]

Investigating and programatically handling administrative changes to a GIS can be an awkward process. If administrative changes were able to trigger a webhook then this could be plugged into a logging mechanism or change management process. In the same way that /item/ can trigger a webhook, /portaladmin/ should as well. 

The end goal of such a webhook would be the ability to write all administrative changes to a file. This record can then be used for diagnostic purposes in the event that a major outage occurs. Current mechanisms would require parsing through web server and application logs.