In order to run the tests in idm-ci we need to configure the our pytest
tests environment variables. This PR configures that automatically if an
environment variable TWD is available and $TWD/config exists.
Until now ansible-freeipa repository only had playbook tests. This
commit introduces the ability of creating TestCase classes connected to
the master host. This connection can be used to run commands in the
managed host after the ansible playbook execution is the allowing the
verification of the machine state.
