ENYO-3576: The Download status data are saved in the project's storage representation instead of relying on a static attribute.

Link to the JIRA ticket: https://enyojs.atlassian.net/browse/ENYO-3576

Ready for review.

Tested on Chrome(Windows 7)
Enyo-DCO-1.1-Signed-off-by: Rafik Adiche mahmoud-rafik.adiche@hp.com