Enable configuration of Identity API v3

* Default IDENTITY_API_VERSION to '2.0' in stackrc

Note: the value of these *_API_VERSION variables will NOT include
the leading 'v' as the CLI tools do not allow it.

Change-Id: I78e0ed5f1baaf236bf95ddf73be764072674d732
Merge branch 'identity-v3' into dt-test
Merge branch 'screen-stop' into dt-test
Merge branch 'update-usb-tools' into dt-test