Ensure that modifications are tracked by ShardTransaction

As modifications are made on a ShardTransaction they are applied to the transaction object that ShardTransaction wraps
However the modifications also need to be tracked. This tracking would be used ultimately by the Shard when persisting data.

Change-Id: I96061aa66a1cf3a9f225012bb22667504cfb3469
Signed-off-by: Moiz Raja <moraja@cisco.com>