Update published event to include header and body

Originally, the published event only contained the raw graph
request payload.
This has now been updated to include the following changes:
- encapsulate the graph request in a body property
- add new event header with details such as timestamp, request-id,
  event-type

Issue-ID: AAI-954

Change-Id: I780b6f52a01aafdcd7d09156e9d3a99c25be90a3
Signed-off-by: Michael Arrastia <MArrasti@amdocs.com>