Increase zindex of item in dragged state (sucks)
Fixed the z-index issue when dragging an item over a topic that has
already been dragged before.
Modified the angular-dragdrop vendor directive, since it was setting the
z-index to 99999 on drag and never setting it. Any subsequent drag
operations would be positioned under that, unless they provide a larger
z-index (lame).
Try a little scale effect on drag over