raftexample: fixes from go vet, go lint

contrib/raftexample/kvstore.go

@@ -64,13 +64,13 @@ func (s *kvstore) readCommits(commitC <-chan *string, errorC <-chan error) {
 			return
 		}
 
-		var data_kv kv
+		var dataKv kv
 		dec := gob.NewDecoder(bytes.NewBufferString(*data))
-		if err := dec.Decode(&data_kv); err != nil {
+		if err := dec.Decode(&dataKv); err != nil {
 			log.Fatalf("raftexample: could not decode message (%v)", err)
 		}
 		s.mu.Lock()
-		s.kvStore[data_kv.Key] = data_kv.Val
+		s.kvStore[dataKv.Key] = dataKv.Val
 		s.mu.Unlock()
 	}
 	if err, ok := <-errorC; ok {

contrib/raftexample/listener.go

@@ -42,9 +42,9 @@ func (ln stoppableListener) Accept() (c net.Conn, err error) {
 		tc, err := ln.AcceptTCP()
 		if err != nil {
 			errc <- err
-		} else {
-			connc <- tc
+			return
 		}
+		connc <- tc
 	}()
 	select {
 	case <-ln.stopc: