Apply "actions" hash to View, Controller & Route action handling

WIP

This PR makes view, controller & route action handlers expected to be defined on an `actions` object.

The previous locations are deprecated (i.e. defining action handler functions directly on the view, directly on the controller, and in an `events` object on the route).

This makes action-handling consistent across Ember.

Some developers expressed concern that "actions" was a part of the domain language of their app. To mitigate the impact on these apps, this PR makes Ember will automatically rename `actions` to `_actions` behind the scenes. This allows an ObjectController to proxy to a model with an `actions` attribute, even if you have an `actions` object defined on the controller.

Note: this PR relies on a change to tildeio/router.js, which I have included in this PR as a separate commit for discussion purposes. When this PR is ready, I will make a separate PR for the router.js project, to be applied first. I have a already prepared a test for the new functionality. 

Specific comments on the code in this PR can go here. The general discussion about action handling in Ember here: http://discuss.emberjs.com/t/the-future-of-the-events-hash/1630/26