Add CSS transition support

It sure would be nice if you could do something like

```hbs
{{#lio-content disableTransitions}}Your mom.{{/lio-content}}
```

I agree that reads well, but only because it's effectively being used as an action. Like

```js
new LioContent().disableTransitions();
```

So in that context, I don't think it should be changed.

As for the convention, I don't think a naming pattern would suffice. What do you think about grouping them in the component definition, and if we're feeling really fancy, having docs?