[WIP] Remove cards and atoms before teardown or re-rendering.

[abuiles]

I was getting trolled with the following error:

Assertion failed: Error: ember-wormhole failed to render into '#__rendered-mobiledoc-entity-1332' because the element is not in the DOM(…)

After chasing it down, the problem was that the editor was being teardown while cards and atoms were still in the list, so wormhole was trying to render but failing.

@bantic I think this is also related with #19

It would be nice to add some tests, but I haven't had the time to do that yet.

[bantic]

@abuiles I think PR #23 addresses the same issue you're reporting here. It's merged and released on a beta version v0.5.3-beta.1. Could you try that out and see if it fixes the issues you've seen in your app? thanks!

[abuiles]

@bantic I'm not 100% sure if this fixes the original issue or not, but now we have a new problem, cards are not being rendered I put an example app where you can see the issue https://github.com/abuiles/_______ember-mobiledoc-dom-playground

This is what I used to get http://s.abuiles.com/2s2i343p0L0e and this is after upgrading to beta http://s.abuiles.com/0e2M2R0i0W2z