Support owners instead of container in Ember 2.3

[offirgolan]

Reference: http://emberjs.com/blog/2015/11/16/ember-2-2-released.html#toc_introducing-owners-and-deprecating-containers

[rwjblue]

Using ember-getowner-polyfill addon to always be able to use the new API should be the easiest way forward.

Other addon updates:

• Use public API for container/registry when possible. emberjs/data#3912
• Fix getOwner container deprecations for Canary. ember-animation/liquid-fire#388
• Use public API for container / registry functions. jamesarosen/ember-i18n#336

ember-test-helpers updates included in 0.4.16 (from emberjs/ember-test-helpers#118 and emberjs/ember-test-helpers#119).

[offirgolan]

Awesome! Thanks for the addon and the starting point Rob!