return low-level mode rather than go's version of it

This allows using the standard stat.S_IS* funcs in python

api.go

@@ -182,7 +182,7 @@ type stat struct {
 	Name  string `json:"name"`
 	Size  int64  `json:"size"`
 	MTime int64  `json:"mtime"`
-	Mode  uint32 `json:"mode"`
+	Mode  int    `json:"mode"`
 }
 
 // args: abspath glob pattern
@@ -196,11 +196,12 @@ func (s sftpAPI) doListdir(path string) ([]stat, error) {
 	}
 
 	for _, st := range infos {
+		x := st.Sys().(*sftp.FileStat)
 		stats = append(stats, stat{
 			st.Name(),
 			st.Size(),
 			st.ModTime().Unix(),
-			uint32(st.Mode()),
+			int(x.Mode),
 		})
 	}