Fixes Ember-data-870 Lazy destruction + App#reset issues

Deleting the container during reset should complete before
we rebuild the container. This fixes an outstanding ember-data
issue -> https://github.com/emberjs/data/pull/870
Merge pull request #2483 from stefanpenner/lazy_destruction_during_reset_is_dangerous

Fixes Ember-data-870 Lazy destruction + App#reset issues