Add an extra test for the `loadingHeight` config for jqc.view.Collection.
Add `is()` method to jqc.ComponentQuery
Add `isDescendantOf()` method to jqc.Component
Update Controller doc to change the `view` config to say that it only accepts a single jqc.Component, instead of an array of Components.
Add jqc.app.EventBus singleton, which allows for a subscription to all jqc.Component-fired events.

This will be used by jqc.app.Controller to implement its event listening functionality.
Fully implement event listening for Controllers. The `listen()` method handles this functionality.
Doc fix in CollectionView. Incorrect @link.