Supports both SQL and templated keystone backend.
Create an additional endpoint for nova api v3.
The service type is computev3.
The endpoint is similar to the v2 one but the version
part is "v3" rather than "v2", and it does not include
the tenantid anymore.
Fixes: bug #1191798
Change-Id: I86e4734c3a9e57f1dc68f1104449d7c041d6927d
806233e0ed