Added newSize and newPosition arguments to callbacks for stop events' handlers

Sometimes there is no way to get the actual new size or position of widget in arguments that you can find in the stop callbacks. I faced this problem today and also found an issue raised by another developer (#185) so I've added them as 4th argument in resizable.stop and draggable.stop callbacks calls.

Current change will not break existing applications.

Here are two screenshots that can probably describe situation better:
- https://dl.dropboxusercontent.com/u/106703/gridster/screen1.png
- https://dl.dropboxusercontent.com/u/106703/gridster/screen2.png