Fixed bug with promises on startup. Fixes #2756.

This bug would cause your app to break if you refreshed
the page on a route the returned a promise in `model`.
Merge pull request #2759 from machty/promise-startup-fix

Fixed bug with promises on startup. Fixes #2756.
Remove ember-testing from production build
Merge pull request #2761 from teddyzeenny/ember-testing-build

Remove ember-testing from production build
Merge branch 'master' of git://github.com/emberjs/ember.js