Routing template

There is patch for ability to set template from routing, like this:

```
pageAwesome:
    path:      /{product}-awesome
    defaults:  { _controller: Bundle:Product:show, _template: Bundle:Product:show-awesome.html.twig}

page:
    path:      /{product}
    defaults:  { _controller: Bundle:Product:show}
```

Use case: I want reuse my controller code for different views, and don't want have if or switch logic and view arguments in controller.
Can be used with Template annotation, or without.

What do you think?