Adds a new API extension for accessing the recorded actions and events
on an instance. Usage is documented with api samples.
Additionally it modified the db api to retrieve actions by request_id
since the api does not return the db id. This extension is the first
consumer of that method so there's no issue of changing behaviour
elsewhere.
Blueprint instance-actions
DocImpact
Change-Id: I74109586cc762a7f51d2b114896cf071ee0671cb
