removes the new isolatedContainer in setup

removes the new isolatedContainer in setup and instead does a ```container.reset()``` in teardown.

see https://github.com/stefanpenner/ember-app-kit/issues/568 for the reason.

i'm not sure if it's the right way to go but i added tests for the component and all test (including the controller needs tests) are green.

@stefanpenner @rpflorence any objections?