Use auth_token from keystonemiddleware

auth_token middleware in python-keystoneclient is deprecated and has
been moved to the keystonemiddleware repo.

This patch updates Ironic to use the new keystonemiddleware package.

Change-Id: Ifb48996867f9f51c4dbedde0e0d9476c2d2818b4
Closes-Bug: #1342274
Merge "Use auth_token from keystonemiddleware"