ENYO-3753: change the button label of the Phonegap Authentication pop-up  from "cancel" to "done".

Link to the JIRA ticket: https://enyojs.atlassian.net/browse/ENYO-3753

Ready for review.

Tested on Chrome(Windows 7)
Enyo-DCO-1.1-Signed-off-by: Rafik Adiche mahmoud-rafik.adiche@hp.com