Adds to Keystone to convert V2 endpoints to V3

The Domain Quota Management Driver uses the V3 Authentication Token.
Also, it tries to contact Keystone for getting list of projects in a
domain using V3 API like /v3/projects?domain_id=<id>. But the
keystone v3/client.py default uses V2 API and hence code changed
to convert V2 endpoints for V3 endpoints. This change is required
to implement blue print domain-quota-driver-api

Change-Id: If62ffc5e5252477bbe4d80f14c0a7653e11d5403
Closes-Bug: 1260916
Merge "Adds to Keystone to convert V2 endpoints to V3"