Added new context method setWithFeedback(), which returns promise, that is passes to the context changing event callbacks and can be manually deferred and completed by them. This is useful when there is a need to know when the behaviour is already acknowledged and reacted to the context param change.
* introduced ListHelper with very clever method to compare to lists and help behaviour-classes to handle complex changes of their lists
* fix in collection - added cloning of the models list when refreshing to be able to find out differences from the old list
* added Widget::dropChild() method to support dynamically removing of list items.