filer store adds kv support

can compile now, need to implement those unimplemented

weed/filer/redis/universal_redis_store_kv.go

@@ -0,0 +1,42 @@
+package redis
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/chrislusf/seaweedfs/weed/filer"
+	"github.com/go-redis/redis"
+)
+
+func (store *UniversalRedisStore) KvPut(ctx context.Context, key []byte, value []byte) (err error) {
+
+	_, err = store.Client.Set(string(key), value, 0).Result()
+
+	if err != nil {
+		return fmt.Errorf("kv put: %v", err)
+	}
+
+	return nil
+}
+
+func (store *UniversalRedisStore) KvGet(ctx context.Context, key []byte) (value []byte, err error) {
+
+	data, err := store.Client.Get(string(key)).Result()
+
+	if err == redis.Nil {
+		return nil, filer.ErrKvNotFound
+	}
+
+	return []byte(data), err
+}
+
+func (store *UniversalRedisStore) KvDelete(ctx context.Context, key []byte) (err error) {
+
+	_, err = store.Client.Del(string(key)).Result()
+
+	if err != nil {
+		return fmt.Errorf("kv delete: %v", err)
+	}
+
+	return nil
+}