extended tstruct for templating

- tstruct is in new datastructure.go
- updated fstab.ww to new syntax

internal/pkg/warewulfconf/datastructure.go

@@ -52,9 +52,9 @@ type NfsConf struct {
 
 type NfsExportConf struct {
 	Path          string `yaml:"path"`
-	ExportOptions string `yaml:"export options"`
-	MountOptions  string `yaml:"mount options"`
-	Mount         bool   `yaml:"mount"`
+	ExportOptions string `default:"rw,sync" yaml:"export options"`
+	MountOptions  string `default:"defaults" yaml:"mount options"`
+	Mount         bool   `default:"true" yaml:"mount"`
 }
 
 func (s *NfsConf) UnmarshalYAML(unmarshal func(interface{}) error) error {
@@ -70,7 +70,6 @@ func (s *NfsConf) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	return nil
 }
 
-
 func init() {
 	if !util.IsFile(ConfigFile) {
 		wwlog.Printf(wwlog.ERROR, "Configuration file not found: %s\n", ConfigFile)
@@ -86,4 +85,4 @@ func init() {
 
 func DataStore() string {
 	return cachedConf.Warewulf.DataStore
-}
+}