Couldn't we just make this a filter for displaying the amount or a provided string if `!amount` rather than making it activation key specific?

Look at [`unlimitedFilter`](https://github.com/Katello/katello/blob/master/engines/bastion/app/assets/javascripts/bastion/incubator/format/unlimitedFilter.filter.js).  It's basically the same thing except it displays "Unlimited" instead of "Automatic".  I think we should combine the two and use it like this:

```html
<p>{{ subscription.amount | displayIfZero:'Automatic'}}</p> 
```

```js
var quantity = displayIfZeroFilter(subscription.quantity, gettext('Unlimited'));
```