Init V4 community edition (#2265)

* Init V4 community edition

* Init V4 community edition

application/migrator/model/source_link.go

@@ -0,0 +1,16 @@
+package model
+
+import (
+	"github.com/jinzhu/gorm"
+)
+
+// SourceLink represent a shared file source link
+type SourceLink struct {
+	gorm.Model
+	FileID    uint   // corresponding file ID
+	Name      string // name of the file while creating the source link, for annotation
+	Downloads int    // 下载数
+
+	// 关联模型
+	File File `gorm:"save_associations:false:false"`
+}