Bug in AbstractLeader replication consensus

In determining whether to advance the commit index, only the voting
members should be counted in the replicatedCount.  There was a logic
error that instead caused it to be incorrectly based on whether the
AppendEntriesReply message as sent by a voting member.

This patch fixes the issue.

Change-Id: I6efb9574c39db608351297fc2552689d1ff77979
Signed-off-by: Gary Wu <gary.wu1@huawei.com>