Colorize Ansible output, and don't buffer output.

Setting environment variables for the ansible-playbook invocation.

ANSIBLE_FORCE_COLOR will ensure output is colorized.  PYTHONUNBUFFERED will stream output as Ansible runs, vs getting a big dump of output at the end.
Merge pull request #1585 from Tpbrown/ansible-color-and-unbuffered

provisioner/ansible: Colorize Ansible output, and don't buffer output.