fixes on secop gui

- do not display a dialog when a command returns None
- apply fmtstr, if available

Change-Id: I74da3e86e4eae9000608581e0a0f6e8c72cef715

secop/gui/modulectrl.py

@@ -165,7 +165,8 @@ class ModuleCtrl(QWidget):
             result = None
             qualifiers = {}
             # XXX: flag missing data report as error
-        showCommandResultDialog(command, args, result, qualifiers)
+        if result is not None:
+            showCommandResultDialog(command, args, result, qualifiers)
 
     def _initModuleWidgets(self):
         initValues = self._node.queryCache(self._module)