* Check minimal API and docker-py versions for all docker_* tests.
* Improve docker_swarm creation/destruction for tests.
* Fail when conditions aren't met.
* Don't hardcode address for advertise_addr.
These tests are doing string matches on the error condition. Update
them to match the new strings. This is probably okay to push out to old
releases even though it's technically backwards incompatible because
production playbooks won't be checking that a parameter was missing.
Param missing is something detected and fixed while writing the playbook.
* Add new Fedora docker images with Python 3.
* Use consistent env var for lookup test.
* Fix testing of virtualenv with Python 3.
* Fix docker_secret tests on Fedora 26.
* Add Python 3 support to Fedora postgresql test.
* Add Python 3 support to Fedora mysql tests.
* Fix uri test server for Python 3 on Fedora.
* Fix iso_extract test for Python 3 on Fedora.
* Add Python 3 support for Fedora to openssl tests.
* Fix dnf group test for Python 3 on Fedora.
* Use force with user deletion in become test.
