CPS Delta API: Update action for delta service

- Added code for Update action in Delta service
- added method to get updated Leaf data: getUpdatedLeavesBetweenSourceAndTargetDataNode
- added method to compare Leaf data common in source and target data
  node
- added method to process leaves unique to target data node
- added method to compare leaves: compareLeaves
- added method to store updated data to a DeltaReport: addUpdatedLeavesToDeltaReport
- Added corresponding testware

Issue-ID: CPS-1824
Signed-off-by: Arpit Singh <as00745003@techmahindra.com>
Change-Id: I3de07ea3227988784a0892f6a92c238ecf00a7fa
6 files changed