Various enhancements & cleanups

1. Make sure constraint objects can be something else than strings (i.e. objects with several properties)
2. Make sure that one can plug an alternative to dojox/css3/transit by setting the transit property on the app config to another AMD module (and build support for that)
3. Refactor LayoutBase so that it is even easier to create subclass by concentrating on the few needed tasks (we could go even further in initLayout I think)
4. Refactor Transition to recurse only once to get both the transition and the default transition.
5. Make sure we can animate when removing a view or adding a new view at a position without a previous view
6. move layout.js to utils like other utils no need to have several utils directory.