default behavior is broken for render  :action_name

doesnt work:

```
render :show
```

works:

```
render :action => :show
```

error is:

```
undefined method `[]' for :show:Symbol
liquidizer-0.5.3/lib/liquidizer/controller_extensions.rb:49:in `liquid_template_for_view'
liquidizer-0.5.3/liquidizer/controller_extensions.rb:20:in `render'
```
