Skip CLI tests is identity v2 is not available

CLI tests rely on identity v2 API. If v2 is configured as not
available skip all CLI tests.

Change-Id: I06f444c9712e2df675c596bf59cec71029a63c34
Partially-implements: bp/multi-keystone-api-version-tests
diff --git a/tempest/cli/__init__.py b/tempest/cli/__init__.py
index 76aafd8..6733204 100644
--- a/tempest/cli/__init__.py
+++ b/tempest/cli/__init__.py
@@ -68,6 +68,14 @@
 
 
 class ClientTestBase(test.BaseTestCase):
+
+    @classmethod
+    def skip_checks(cls):
+        super(ClientTestBase, cls).skip_checks()
+        if not CONF.identity_feature_enabled.api_v2:
+            raise cls.skipException("CLI clients rely on identity v2 API, "
+                                    "which is configured as not available")
+
     @classmethod
     def resource_setup(cls):
         if not CONF.cli.enabled: