Move all the dom-things to use the dom service in tabular-collection, feedback-dialog, list-collection and node show. Move get-component-factory into utils/dom and use dom.root() in a few more places
This includes an additional `dom.components` method which gives you a
list of components matching the selector instead of just one.
The original version of ember-block-slots doesn't support ember 3 and it
seems like development has stalled on the original version.
This adds a modified version as an in-repo-addon that is compatible with
ember 3.