OO-1808: show a message if the course element cannot deliver a view after an author published the course

no-jira: small selenium test to create and delete a business group, selenium to test concurrent editing of a course

OO-1616: fix the certificate unit test in the REST API suite, don't doInSync during import of the course, remove get resource method (duplicate), remove unused constructor and method

no-jira: add selenium test for the direct deletion of user, remove empty info in the panel to create a business group, add the missing parameter of the uploaded by i18n key in different languages

no-jira: add a user prefs.js for FireFox to prevent password saving, Firefox homepage with last version 42...

OO-1593: revert the custom identity mapping, too much side effect, it would need a refactoring of the IdentityImpl mapping