Update the Image Reorderer documentationI to reflect the new, selector-based approach we are recommending for all users.

At the moment, the Image Reorderer documentation refers to the old id-based scheme for locating elements in the DOM. We should update the API and other documentation to reflect the simpler approach and bring it more in line with our Image Reorderer demo.

This should also include integrating the new afterMove callback tutorial located here:

http://wiki.fluidproject.org/display/fluid/Talking+to+the+Server+Using+The+afterMove+Event