Add acceptance test for uncaught exception in controller init

Added a failing test to reproduce an uncaught exception thrown from a controller's `init` function...  See emberjs/ember.js#3829

I wasn't sure if I can use the `Ember.Test.adapter = Ember.Test.QUnitAdapter.create({})` twice in the same test function to change the exception handler, so I created a separate test function, after `Unhandled exceptions are logged via Ember.Test.adapter#exception`... So, please let me know if this can be implemented within the same test.  This is my very first pull request for ANY open source project!! :)

I'd be willing to come up with a fix for this as well, but it may take some time as I still need to familiarize myself with the whole project.

Thanks,
Ian