Initial support for OpenStack Keystone

We now use OpenStack Keystone as our backend for authentication /
authorization. This moves our user management outside of stripe and
allow for integration with services such as LDAP.

Change-Id: Ie0f8ad610df70e1004dcd4ad77ae9ab84fa9a88d
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>