The instance action notifications contain the user id and the
project id of the owner of the instance. However an instance
action might be initiated by another user. It could be another
user from the same project or can be an admin from the admin project.
To be able to distinguish between the user who initiated the instance
action from the user owning the instance we need to add two new
fields to the instance action notifications, action_initiator_user
and action_initiator_project
Change-Id: I649d8a27baa8840bc1bb567fef027c749c663432
Closes-bug: #1744658
Blueprint: add-action-initiator-to-instance-action-notifications