OF-2880: Admin console should not show directory listing
When browsing to `/images/` (or another endpoint with no welcome page), Openfire should not show the index of the directory.
(cherry picked from commit 7de9664586747d82a9279442387386cf23d31890)
OF-2884: Fix group user removal when making it admin
When a user of a group is made an 'admin' of the group, its removal from the 'members' group should not cause it to be removed from the group completely.
(cherry picked from commit 62deaeefde026ab656dbf74ff41e78770b065dbc)