- Include OpenBSD 5.9 in supported OSes.
- Better assertions.

- Enable free Ansible strategy to allow each host to proceed as fast as it can to help speed up some plays.

- Caching the entire virtualenv in Travis CI has proven to cause issues, caching just pip's cache directory.

- Use privileged container instead of just adding the sys_admin capability (the latter has been shown to be cause unrelated issues).

- Remove mention of tests/requirements.yml from the Requirements section in the README, relevant only for testing.