Update ember-test-helpers version.
Update ember-test-helpers version.

Adds Ember 2.0.0-beta.3 compatibility.

emberjs/ember-qunit,emberjs/ember-qunit,MattNguyen/ember-qunit,OrKoN/ember-qunit,MattNguyen/ember-qunit,aceofspades/ember-qunit,tsing80/ember-qunit,MattNguyen/ember-qunit,rwjblue/ember-qunit,tsing80/ember-qunit,tsing80/ember-qunit,UmangSardesai/ember-qunit,rwjblue/ember-qunit,UmangSardesai/ember-qunit,OrKoN/ember-qunit,aceofspades/ember-qunit,aceofspades/ember-qunit,OrKoN/ember-qunit,UmangSardesai/ember-qunit