Update ember-dev gem to latest version

I ran `bundle update ember-dev` so the gem is updated to the latest version,
which upgraded QUnit to v1.11.0, see https://github.com/emberjs/ember-dev/commit/806acd126dbf46253500222fd5f47e156899bbf0
Merge pull request #2375 from pangratz/update/ember-dev

Update ember-dev gem to latest version