[DOC release] Added tabindex to Link docs

Conflicts:
	packages/ember-routing-views/lib/views/link.js
[DOC release] Documented Evented for Router
[BUGFIX release] Fix hasThis lookup regression

Also optimizes lookup using lastIndexOf(x, 0), resulting in a constant time lookup
[BUGFIX beta] Only register this observer in debug builds
[Bugfix beta] just initialize views in preRender
[BUGFIX beta] Rewrite with transform to use block params
[DOC release] Document final argument for transitionTo/transitionToRoute.

Adds documentation for a final options argument for the
`Controller#transitionToRoute` and `Route#transitionTo` methods.
Use Node 0.11.
[BUGFIX beta] Make CollectionView _contextBinding one way to eliminate an unnecessary observer
[BUGFIX beta] Avoid defineProperty calls on _context & controller
[BUGFIX beta] `View#element` should not be observable
[BUGFIX beta] Avoid reading current values while setting during initialization

Credit goes to @krisselden for this one. We’re unnecessarily reading values out of the prototype to conditionally notify, but notification is short circuited during initialization inside of propertyWillChange & propertyDidChange.
[BUGFIX beta] `classNameBindings` and `attributeBindings` are concatenatedProperties that should never be a computed property. Therefore, we don’t need to use `get` here.
[BUGFIX beta] It’s possible for `tagName` to be an empty string and therefore we shouldn’t fallback to `get(view, ‘tagName’)`
[BUGFIX beta] Avoid unnecessary work being done for SimpleBoundView due to it not having `tagName: ‘’` specified