[NbtkGtkExpander] add gobject properties for label-widget and has-indicator
[NbtkGtkExpander] add gobject properties for label-widget and has-indicator

jonnylamb/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx