This commits handles the case where config transaction of
type B is submitted and Raft cluster quorum fails/shutdowns.
During startup, leader compares last known configuration with Raft
config state and if there is a difference, finalize reconfiguration by
proposing delta.

Change-Id: I3cdf03533602489cb56c503f1d6651f27a5fc6a1
Signed-off-by: Artem Barger <bartem@il.ibm.com>