Fixing drag-n-drop for folders in hotseat.

The current drag-n-drop model assums that when a folder is open
it completely covers the folderIcon and its not possible to drop
anything on the icon. But its not true when a folder is in the
hotseat.

> When DnD finishes revert folder to the normal state
> Ensure that only one folder is open at a time
> Prevent folder icon from moving when the folder is open

Bug: 13646281,14680549
Change-Id: I016a4c3f0d9b57c388eaa28f40df9e7b7bbab5fc