signal-composer does not return session uuid on subscribe as expected

The signal-composer documentation shows that the response to subscribing to an event includes the session context uuid.  Currently, it does not, which is a problem for users that need to know the value to be able to generate the full event name string for determining event origin, e.g. bindings/applications based on libappcontroller.  The uuid value should be added to the subscribe response to match documented behavior and enable these users.