Add mapping rules integration tests

This patch adds the tests for the Mappings API (part of the
Federated Identity API).

The tests added here are not intended to cover all negative and
corner cases, they are rather testing the API in a higher level
and its integration in a working environment.

Change-Id: If245a12a407f960a7ad5f73aa7af717229976ea2
diff --git a/keystone_tempest_plugin/clients.py b/keystone_tempest_plugin/clients.py
index 1a85bce..a72c9f5 100644
--- a/keystone_tempest_plugin/clients.py
+++ b/keystone_tempest_plugin/clients.py
@@ -15,6 +15,8 @@
 from keystone_tempest_plugin.services.identity.v3 import (
     identity_providers_client)
 from keystone_tempest_plugin.services.identity.v3 import (
+    mapping_rules_client)
+from keystone_tempest_plugin.services.identity.v3 import (
     service_providers_client)
 
 from tempest import clients
@@ -28,6 +30,9 @@
         self.identity_providers_client = (
             identity_providers_client.IdentityProvidersClient(
                 self.auth_provider))
+        self.mapping_rules_client = (
+            mapping_rules_client.MappingRulesClient(
+                self.auth_provider))
         self.service_providers_client = (
             service_providers_client.ServiceProvidersClient(
                 self.auth_provider))