add cmd 'bee update' to update self

just notice once a day if there is a new version

config/conf.go

@@ -19,12 +19,19 @@ import (
 	"os"
 	"path/filepath"
 
-	beeLogger "github.com/beego/bee/logger"
 	"gopkg.in/yaml.v2"
+
+	beeLogger "github.com/beego/bee/logger"
 )
 
 const confVer = 0
 
+const (
+	Version = "1.12.0"
+	GitRemotePath = "github.com/beego/bee"
+)
+
+
 var Conf = struct {
 	Version            int
 	WatchExts          []string  `json:"watch_ext" yaml:"watch_ext"`