Fix #2840 - textfield binding issue with null
Ember.Test tests refactor
StateManager and states now pass their `container` to child states. @lukemelia/@stefanpenner
Merge pull request #2852 from lukemelia/container-for-statemanager

StateManager and states now pass their `container` to child states.
In StateManager, use instanceof check instead old isState attribute. This is potentially breaking, but very unlikely to affect real-world code.

@lukemelia/@stefanpenner
Merge pull request #2853 from lukemelia/statemanager-cleanup

In StateManager, use instanceof check instead old isState attribute.
Merge pull request #2851 from teddyzeenny/test-refactor

Ember.Test tests refactor
Merge pull request #2841 from mitchlloyd/master

Fix #2840 - textfield binding issue with null