Fix a couple of issues with replication

- First the data that was being sent from the primary was not being deserialized on the followers
- The state on the followers was not being applied correctly
- Add sal-distributed-datastore to the distribution

Added a test for CompositeModificationPayload to ensure that serialization works correctly
Also added a set of integration test programs to test the serialization

Change-Id: Id67d2c4fe471003d9dd3b42a8376c90fd23492ce
Signed-off-by: Moiz Raja <moraja@cisco.com>