raft: use configured logger in raft/node.go

Those three log statements in node.go have not been using the logger that was passed via `raft.Config`, but instead the default raft logger. This changes it to use the proper logger.

raft/node.go

@@ -260,13 +260,13 @@ func (n *node) run(r *raft) {
 		if lead != r.lead {
 			if r.hasLeader() {
 				if lead == None {
-					raftLogger.Infof("raft.node: %x elected leader %x at term %d", r.id, r.lead, r.Term)
+					r.logger.Infof("raft.node: %x elected leader %x at term %d", r.id, r.lead, r.Term)
 				} else {
-					raftLogger.Infof("raft.node: %x changed leader from %x to %x at term %d", r.id, lead, r.lead, r.Term)
+					r.logger.Infof("raft.node: %x changed leader from %x to %x at term %d", r.id, lead, r.lead, r.Term)
 				}
 				propc = n.propc
 			} else {
-				raftLogger.Infof("raft.node: %x lost leader %x at term %d", r.id, lead, r.Term)
+				r.logger.Infof("raft.node: %x lost leader %x at term %d", r.id, lead, r.Term)
 				propc = nil
 			}
 			lead = r.lead