Allow auth_strategy to be toggled

Fix a bug where auth_strategy was hardcoded to keystone.

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

Change-Id: I4a3a05ab56be9819de5dfcdc74ec195b897f6d39
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>