ENYO-2784: Overwrite checking for saved-as files

Related JIRA: https://enyojs.atlassian.net/browse/ENYO-2784

As a file is saved-as, the new target file must be check as exiting or not in order to propose to be overwrite or not.
It implied to refactor ActionPopup.js to be used for the overwriteActionPopup and to refactor in consequency saveActionPopup and ProjectDeletePopup.

Enyo-DCO-1.1-Signed-off-by: Vincent HERILIER vincent.herilier@hp.com