Template controller and view error

* Actually, your `Controller_Haml` is a template controller.
* When you write in an action

```php

class Controller_Welcome extends Controller_Haml_Template {
public function action_index()
{
       // ...
       $view = Haml::factory('index');
       $view->data= "Some data";
```
you get the `Undefined variable $data` error in view

```php
// ...
<?php echo $data ?>
```

If you use

```php
// ...
$view = Haml::factory('index');
$this->data= "Some data"; 
```
you get no error. Here `$this` is the template and it is incorrect approach.