When the user changes the toggle on their device to turn on/off Presence, their device must be able to contact our server so that we can update their Presence choice in the Presence-Authentications table. This is because Presence is broadcast in the background by the SimplePush UA, and we don't want to have to include a list of all the 'apps' that should get the presence update in every ping request.
When Presence gets a status update from simplepush, it looks up the client-id in the Client-Mappings, then uses that
