added sftp client implementation

vendor/github.com/pkg/sftp/ls_plan9.go

@@ -0,0 +1,21 @@
+// +build plan9
+
+package sftp
+
+import (
+	"os"
+	"syscall"
+)
+
+func lsLinksUIDGID(fi os.FileInfo) (numLinks uint64, uid, gid string) {
+	numLinks = 1
+	uid, gid = "0", "0"
+
+	switch sys := fi.Sys().(type) {
+	case *syscall.Dir:
+		uid = sys.Uid
+		gid = sys.Gid
+	}
+
+	return numLinks, uid, gid
+}