This review request changes makes improvements to RB.DialogView. It introduces a property on

RB.DialogView which is a map of buttons in the dialog from button ids to 

button elements. The id field of a RB.DialogView button is now required so that

buttons can be referenced by their id in the map. In addition, disabled and class

are added as button keys so that buttons can be created with initial state set to disabled

and with classes set, respectively.

Unit tests:

- new dialog view button properties (id, class, disabled)