This is a very simple endpoint which allows the satellite UI client to
notify the console server that an event has occurred. We will use this
to track when users have completed certain tasks that can't be tracked
server-side (e.g. generating gateway credentials, setting a passphrase)
As part of this change, one client side event is implemented to use the
endpoint - when the user clicks the button to create gateway credentials
after making a new access grant.
Change-Id: Ic8fa729f1c84474788e1de84c18532aef8e8fa3c
