Create db migrations framework

models/models.go

@@ -15,6 +15,7 @@ import (
 	"github.com/go-xorm/xorm"
 	_ "github.com/lib/pq"
 
+	"github.com/gogits/gogs/models/migrations"
 	"github.com/gogits/gogs/modules/setting"
 )
 
@@ -131,6 +132,11 @@ func NewEngine() (err error) {
 	if err = SetEngine(); err != nil {
 		return err
 	}
+
+	if err = migrations.Migrate(x); err != nil {
+		return err
+	}
+
 	if err = x.StoreEngine("InnoDB").Sync2(tables...); err != nil {
 		return fmt.Errorf("sync database struct error: %v\n", err)
 	}