add default values for SSH settings (#500)

modules/setting/setting.go

@@ -79,7 +79,7 @@ var (
 	LandingPageURL       LandingPage
 	UnixSocketPermission uint32
 
-	SSH struct {
+	SSH = struct {
 		Disabled            bool           `ini:"DISABLE_SSH"`
 		StartBuiltinServer  bool           `ini:"START_SSH_SERVER"`
 		Domain              string         `ini:"SSH_DOMAIN"`
@@ -91,6 +91,12 @@ var (
 		KeygenPath          string         `ini:"SSH_KEYGEN_PATH"`
 		MinimumKeySizeCheck bool           `ini:"-"`
 		MinimumKeySizes     map[string]int `ini:"-"`
+	}{
+		Disabled:           false,
+		StartBuiltinServer: false,
+		Domain:             "localhost",
+		Port:               22,
+		KeygenPath:         "ssh-keygen",
 	}
 
 	LFS struct {