Reduce shell power over user management.

Remove MANAGE_USERS permission from shell and whitelist it for
some specific functionality.

Bug: 29189712
Change-Id: Ifb37448c091af91991964511e3efb1bb4dea1ff3
(cherry picked from commit cd50529e6f7c67b115b5725a52b54d2329f8a6a0)
3 files changed