BUG 1712 - Distributed DataStore does not work properly with Transaction Chains

BUG 1712  - Distributed DataStore does not work properly with Transaction Chains

The fix is as follows,

1. When Creating a trasaction chain create a unique identifier for the transaction chain
   using the member name and the current timestamp

2. When a transaction is created using the transaction chain pass the transaction chain id
   along to the remote shard

3. If the remote shard receives a transaction with a valid transaction chain (one which is
   not empty) then it creates a new transaction chain if one does not exist. If one does exist
   then the Shard just creates a new transaction on the existing transaction chain.
   This way if a single transaction chai was used to create transactions on multiple
   different shards the a transaction chain would  be created on each one of those shards.

4. When a transaction chain is closed a Close Transaction Chain message is broadcast to all
   the Shards in the system. If those shards had a transaction chain with the specified id
   then the transaction chain would be closed. The sender does not care about receiving a
   response

5. When a state change occurs on a Shard we check if the Shard is not a leader. If that is
   the case we automatically close all existing transaction chains on that shard and clear
   the map which tracks the transaction chains for that shard

Change-Id: I6bcfb9de3d0ec666e4152afb69c702dda4f38171
Signed-off-by: Moiz Raja <moraja@cisco.com>