ENYO-2497: Undo the last DragNDrop move action

Related JIRA: https://enyojs.atlassian.net/browse/ENYO-2497

* As a node has been moved with a DnD action, it can be undone right after
* After any file action, the undo capability is canceled

Checked on Windows 7 : Chrome

Ready to be reviewed

Enyo-DCO-1.1-Signed-off-by: Vincent HERILIER vincent.herilier@hp.com