improve latest successful installer save logic for RTA

Change-Id: Ic0d3d4745e7050caf889c43ca7f18853d0d7a07c
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>
Revert "Don't show checkbox for Creator if root on Linux and Mac."

This reverts commit 74f84dd0c5fcb28ab126c1a5d874271616a7b927

Broke RTA

Change-Id: I821dde91980ace48471917b2525a4832ce48203c
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>