The dependencies property was only being called once by the __init__
method so it was removed and the code was moved to the __init__ method.
The tests were updated to reflect this.
The active_child_state property was unnecessary as it was not being
referenced outside the class. This commit removes it and updates the
tests accordingly.
Revised universal media player to cache the active player when updating
the state when any of the children change. Revised tests to accommodate
this change.
1) Removed children property because it was only being used by one
method.
2) Removed option to return state as object from _entity_lkp as it was
no longer needed.
3) Used hass.states.get to get entity state objects.
4) Revised test to remove children property.
Ryan Kraus