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
Define Mixin properties in prototype
fix test not to expect synchronous observers
removing kruft
make tests not depend on synchronous change events
remove sync from render to buffer
Better organize ember-metal and cache function lookups.
More metal cleanup
Add {{input action="foo" on="keyPress"}}
Default text input action to 'enter'
Add {{text area}}
remove unneeded asynchrony from routing tests
Merge pull request #2379 from stefanpenner/removeUneededRoutingTestAsynchrony

remove unneeded asynchrony from routing tests
remove uneeded asynchrony from Ember.Deferred tests
Merge pull request #2380 from stefanpenner/removeAsynchronyFromDeferredTests

remove uneeded asynchrony from Ember.Deferred tests
Improve view container lookup performance
Fix typo
Convert a for in loop to a plain for loop
Use a string instead of an array in RenderBuffer