Bug 1386000: Group homepage to only show submitted items once

Change group homepage so that it does not to show repeated pages/collections in different sections shared/submitted
Updated create_group() in TestingDataGenerator.php to set in the DB the correct group role of a user

Change-Id: I07504f38a35d4dda4a3c4f440d94cffed293bbf2
(cherry picked from commit 33c4a9b7)
(cherry picked from commit 44fe56cb)