Ability to pass AppView options

In `0.4.x` there was the ability to set options in the `appView`. Mainly by overwriting the defaults. In `0.5.0` i seems the `appView` is omitted ( at least in the examples ). So instead of trying to overwrite those defaults I found a way that you can pass options to the `appView` when initializing the app. The main reason you would want to do this is to change the `contentEl` value.

```javascript
var App = window.App = new (require('app/app'))({{json appData}}, {
    viewOptions : {  // this gets passed to the appView
        contentEl : '#main' 
    }
});
```

Clearly the intent was to have this overwritable because `_.defaults( this.options, {});` is already present in the 'rendr/client/app_view'.

Let me know if you would like to revise the way the `viewOptions` are passed.