Added handling of message body received as bytes ("application/json")
to avoid "TypeError: the JSON object must be str, not 'bytes'"
Change-Id: I007b33e1b9f210ede2df5d1e2aa32535222d5d67
Task:24818
Story: 2003533
Signed-off-by: Boris Pilka <boris.pilka@x-works.io>