didn't help.

This reverts commit e1804d8d.

# Conflicts:
#	.travis.yml

# Conflicts:
#	.travis.yml

- Try using Python 3.4 as it seems to be the oldest Python 3 version on which pre-commit tests (according to their Travis CI).

- Build on my supported platforms (some don't have properly working Vagrant boxes so they're allowed to fail).

- 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).