Ability to replace content instead of appending

[trentmwillis]

Looking at the current code, it seems that ember-wormhole only supports appending content into the destination. While this makes sense in a lot of cases, we have a use-case where it would be beneficial to replace the content of the destination instead.

In short, we have a portion of our app being SSR'd and after boot up on the client, we're using ember-wormhole to inject some dynamic content and it works wonderfully. But, for SEO and slower phones, we initially render some placeholder content, which we currently have to manually remove. It would be nice if ember-wormhole could handle that for us.

Edit: if this seems like a reasonable ask, I'll implement it.

[lukemelia]

Closing in favor of discussion on #52