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: Ic6473833be35625282e7442f3c88fc1c4d0cc134
diff --git a/stackrc b/stackrc
index 49cf026..b998def 100644
--- a/stackrc
+++ b/stackrc
@@ -37,6 +37,9 @@
 # Set the default Nova APIs to enable
 NOVA_ENABLED_APIS=ec2,osapi_compute,metadata
 
+# Configure Identity API version: 2.0, 3
+IDENTITY_API_VERSION=2.0
+
 # Whether to use 'dev mode' for screen windows. Dev mode works by
 # stuffing text into the screen windows so that a developer can use
 # ctrl-c, up-arrow, enter to restart the service. Starting services