Without this change the "Import variables specific to distribution"
tasks fail with "Could not find file on the Ansible Controller..."
on environments with inject facts disabled.
This changes the tests to run with ansible with
inject_facts_as_vars = false and fixes other roles and playbooks.
As the old way to include tasks is deprecated, replace static include
statements with import_tasks and dynamic ones with include_tasks.
Increaded the required ansible version to 2.5.0 to make sure that
include_tasks and import_tasks is working as expected.
Fixes issue #38
