Molecule also needs to be bumped to support Ansible 2.10
lint: section changed in Molecule 3.x - adapted.
molecule-docker added do test-reqs because it code has moved to it from
molecule core
pytest-testinfra and pytest-molecule needed for testinfra tests to work

[1]: https://github.com/ansible-community/molecule/issues/2872

Change-Id: I0299f5126ebd080f3912a76294b0013abe7747a0

We run yamllint with the same configuration in kayobe-config, so we
should catch issues here before they are synchronised.

Change-Id: Ia2de07abc7c58040f99766adb950c477800ea56d

Change-Id: I01daebb219a7e1c7ac0803db17efc14e3173561d

Tests operation of the role with default variable values.