Don't turn on sudo for all tasks when setting the sudo_user or ask_sudo_pass

This also relates to to Issue #3297.

If you specify the sudo_user or the ask_sudo_pass values, you shouldn't have sudo be turned on by default for all tasks.  It should still be executed as the currently executing user, and you can then choose to also sudo=true, or do it per playbook or per task within ansible.

Otherwise, you really have no way of specifying the password for a sudo user, and still use the originally executing user to run your tasks/playbooks.