Consolidate V2Controller functionality
Consolidate V2Controller functionality

Since ec2 is the only use-case left for using the V2Controller,
we can consolidate what is left into two v3_to_v2 functions.
These can be removed once ec2 functionality is removed.

Change-Id: I3a4731738efe934238e38567a3c2cf514a3d7f23

mahak/keystone,openstack/keystone,openstack/keystone,mahak/keystone,openstack/keystone,mahak/keystone