raft_consensus: improve logging when detecting leader failure
raft_consensus: improve logging when detecting leader failure

Previously when a peer detected a leader failure, it would log some nonsense
like "failure of peer election-timer". This patch makes it log the actual peer
UUID.

Change-Id: I56748cd12ba143bbdb6739049c46e5e90ab6fade
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/8032
Tested-by: jenkins
Reviewed-by: Michael Percy <e07a1fd797b473a9c849e618aa2ce06d8055760b@cloudera.com>

InspurUSA/kudu,andrwng/kudu,helifu/kudu,InspurUSA/kudu,cloudera/kudu,EvilMcJerkface/kudu,andrwng/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,cloudera/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,andrwng/kudu,cloudera/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,andrwng/kudu,EvilMcJerkface/kudu,andrwng/kudu,cloudera/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,cloudera/kudu,helifu/kudu,helifu/kudu,helifu/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,InspurUSA/kudu,helifu/kudu,helifu/kudu,andrwng/kudu,helifu/kudu,cloudera/kudu,helifu/kudu,andrwng/kudu,helifu/kudu,cloudera/kudu,cloudera/kudu,andrwng/kudu,cloudera/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,andrwng/kudu