Missed file from d8ae187256f1cd9e67d575dd19ac78968a0e029f
Add support to set DefaultRegion on CloudIdentity

When using the SDK with then open source version of OpenStack, we need
to specify a region on every single method call on IComputeProvider,
since OpenStack does not allow to configure default region on the user.
This change adds the option to set a default region on the CloudIdentity
that overrides whatever is retrieved from the server.