AccessKeyed should observe the object[key]

[jdanyow]

Currently AccessKeyed sets up an observer for the property that accesses the object instance (scope.object) and the property that accesses the key value (scope.key) but it does not observe the object's property identified by the key.

The current behavior makes sense when the object is an array instance (although it's been argued that Aurelia should use dirty-checking in cases where AccessKeyed accesses an array).

Plunker demonstrating the issue (thanks @mattduffield)