Passes the Keystone token_format Parameter

Previously, the openstack module did not support managing the
Keystone token_format.

Adds the token_format parameter for managing Keystone auth tokens
as either PKI or UUID.  Defaults to PKI for backwards
compatibility.

This patch is based on the following patch from master:
  https://review.openstack.org/#/c/43004/

Change-Id: I6a88fbeac78b3f8b1116db74e18004251a2e5bcf