BUG-421: Define multipart-transaction-aware

This bundles up the 'moreReplies' leaf into a grouping, as it is used in
multiple places. The new multipart-transaction-aware is used instead,
resulting in a common class shared between the notifications, which
should allow for better code reuse.

Change-Id: If225ba4a24d64158893c9f67b5115a6b8b19fcd9
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge "BUG-421: Define multipart-transaction-aware"