* Update Shippable integration test groups.
* Update integration test group aliases.
* Rebalance AWS and Azure tests with extra group.
* Rebalance Windows tests with another group.
include_vars will now also return a key 'ansible_included_var_files'
which contains the list of files that were successfully loaded.
This is useful information and, amongst other things, a way for users
to know exactly what files were included when debugging their
playbooks.
This also allows us to improve the integration tests around
include_vars.
