Clearer error message in replace method

Previous message was unclear for me (or I understood it wrong). It sound like I can't nest a view in already nested parent. I suppose the real meaning should be that I can't nest a child in a parent, if the child is already nested somewhere else.
Conflicts:
	packages_es6/ember-views/lib/views/container_view.js
Fix typo.
[BUGFIX beta] Update backburner.js.

Update with fixes for IE8 by @tricknotes (THANKS!).