[BUGFIX release] Ensure ember-testing is not included in build output.

Conflicts:
	Brocfile.js
	lib/packages.js
[BUGFIX beta] Do not use defineProperty on each View instance.

Conflicts:
	packages/ember-views/lib/views/core_view.js
Release 1.7.1.
Update CHANGELOG.
Merge remote-tracking branch 'emberjs/stable' into stable