Bug 3206: CDS - issues with direct commit

Bug 3206: CDS - issues with direct commit

Modified RaftActor#persistData to send the ApplyState message instead of
calling applyState directly in case the Shard tries to persist another
entry during the persist callback.

Modified Shard to use the correct sneder to send the
CommitTransactionReply message.

The third fix is to ensure direct commits in a chain aren't committed
before previous coordinated commits. In the ShardCommitCoordinator, I
changed it to enqueue all CohortEntries when they are readied so they
are processed in that order.

I also included the unit test scenario that caused the issues to occur.

Change-Id: I65ffcbbac37d6be28c4e1c2dc17d3b0ca21847dc
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>