Install acl package for become-user tasks

All the pain with world-readable temp files and Ansible deprecation
warnings goes away witih this package. :)

platon.yml

@@ -18,6 +18,8 @@
           # Should come from ble-keeper-role
           # see https://github.com/netz39/ble-keykeeper-role/issues/4
           - python3-pip
+          # This is needed for the user-executed tasks
+          - acl
           # Regular packages
           - tmux
           - git-core