The intention here is to provide better integration between what
oslo.context expects and what keystonemiddleware provides. As auth_token
middleware changes each service has to react independently to the new
options and the way they build contexts.
By providing a helper here we can improve the consistency across
services to standardize the options and provide a common way to react to
auth_token middleware improvements.
Change-Id: Ic590b3ee359e9a9c27eef3d11c0738066f475881
1f3719dfcf