Unbuffered output for seeing the progress of an ansible run

Previously the whole ansible run was buffered. It would run for e.g. 15 minutes and you would see nothing until the run completed or failed.

By setting `PYTHONUNBUFFERED=1` the output will be flushed immediately (or at least more often) so you can see the progress of the ansible run.

Also added `ANSIBLE_FORCE_COLOR=true` to get the green (stdout) / red (stderr) colored output as configured in provisioner.rb