New File Upload widget

In the same time we migrate to JSF 2, since there is work to do for having the widget work, we should update the file upload widget and re-implement it using a javascript based solution (or at least evaluate the option)

This widget is very often use in the platform but it no longer corresponds to today's uses in term of file upload.

User needs to add or remove its file faster:

• the comprehension of the field should be immediate
• the feedback in case of wrong file (too heavy, not supported / relevant extension) should be done before the upload
• the widget should be consistent (for now there is 2 lines if you don't have no file - none & upload -, 3 if you already have a file - keep, upload, delete.). It complicates the understanding for users that are already familiar with file upload (mails, facebook, …)