ENYO-2151: add Drag&Drop feature for project file tree

* Files & folders can be moved with a drag'n'drop action through the project file tree.
* Files & folders drag'n'drop is provided with mouse cursor which indicates if it's possible or not to perform the action
* Copy & rename commands for the file system have been updated to use more parameters than name only... 

NB: related "package.js" files are not updated yet

Tested Browsers (under Windows 7) are:
* Firefox 21
* Chrome
* Chrome Canary
* Opera
* Safari 4 Windows
* IE 10

Enyo-DCO-1.1-Signed-off-by: Vincent Herilier <vincent.herilier@hp.com>