- Updated Jenkinsfile to use Tox.

- Remove Jessie from allowed failures in TravisCI (the problem with the image download was resolved).

- Share the Tox directory just between the Molecule tests (sharing between the Molecule tests and pre-commit, which have different dependencies, causes every change to rebuild the virtualenv).

- Disable testing on Python 3.5, it isn't supported by Molecule and doesn't seem to gonna be supported anytime soon.

- Remove OpenBSD 5.9 platform from testing, it never worked and it's not supported upstream anymore now that OpenBSD 6.1 was released.

- Correct assertion for Ansible 2.3.0.0 (ansible_distribution_release and ansible_distribution_version were reversed for OpenBSD prior to that version).

# Conflicts:
#	.travis.yml

- Don't cache .tox, packages aren't updated.

# Conflicts:
#	tests/requirements.txt

- Removed piprot dependency since it's used only with pre-commit and now it's installed inside the hook's virtualenv.