Vendor upstream redis library instead of our fork. (#3913)

We forked the upstream to address a build issue on
go 1.6 - that is long done and we don't need
to manage our forks anymore.

cmd/notify-redis.go

@@ -21,7 +21,7 @@ import (
 	"time"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/minio/redigo/redis"
+	"github.com/garyburd/redigo/redis"
 )
 
 // redisNotify to send logs to Redis server