With the keystone_config provider inheriting from the openstack_config
provider we can now add acceptance tests in openstacklib to be sure that
all the dependant providers (every config provider in every
puppet-openstack modules) behave correctly.
Change-Id: I4dce9b8a89139f0b37f5c92dd9acf608e16ee6c1
Depends-On: I7c880518f0323e44e7c72f0ff5548482a0b1413c