2.0 Modal - Add ability to cancel hide

Created by: ansman

I require the ability to cancel the hiding of a modal when the user for example clicks on the backdrop or presses escape.

The reason is I wan't the user to press a done button to close (to make sure they understand the implications of closing it).

I'd like options for a confirmShow and confirmClose option which will be called before and which will abort the showing/hiding if that function returns false.