Add the list of Raft peers to Consul's Stats

```
% consul info
[snip]
raft:
[snip]
	raft_peers = 127.0.0.1:8300
[snip]
```

Poached from: Nomad Project

consul/server.go

@@ -11,6 +11,7 @@ import (
 	"path/filepath"
 	"reflect"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -743,6 +744,11 @@ func (s *Server) Stats() map[string]map[string]string {
 		"serf_wan": s.serfWAN.Stats(),
 		"runtime":  runtimeStats(),
 	}
+	if peers, err := s.raftPeers.Peers(); err == nil {
+		stats["raft"]["raft_peers"] = strings.Join(peers, ",")
+	} else {
+		s.logger.Printf("[DEBUG] server: error getting raft peers: %v", err)
+	}
 	return stats
 }