[review #17] Models: Use getUserStateFromRequest on populateState

Please review the changes for this one view, then we may proceed for all.

Here class is extended from `JModelForm` https://github.com/joomla-projects/com_localise/blob/develop/component/admin/models/language.php#L21 that's why we can use,

```Php
$name = $this->getUserStateFromRequest($this->_context . '.name', 'name');
```

_Question: We should use `JModelAdmin` here or it's fine with `JModelForm`?_