Ember.Application is now a thenable

app = Ember.Application.create()
app.then(function(){
  // will fire when the appDidBoot
  // very similar to #ready
});

can be used to prevent test runs
before the app is ready.

before(function(done){
  app.then(done);
});
Merge pull request #2343 from stefanpenner/master

Ember.Application instances are now Deferreds.